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Chemistry Lecture 7 For General Chemistry and InOrganic Chemistry — Transcript

by Jan Bernel Padolina · 7,824 words · 1,586 segments · language en · Watch on YouTube

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0:01Okay. So, chapter 7, quantitative
0:04composition of compounds.
0:08Okay. So, in this uh introduction to
0:14this topic, no? So, sabi dito, "These
0:17candies are formed of a sweet center,
0:21no? Covered in layers of sucrose. The
0:25candies can be measured by either
0:28weighing or counting. No so ah sa
0:32chemistry no we we are implementing no
0:37different ways of calculations no so
0:41marami maraming way on on how to
0:43calculate things maraming route. Okay?
0:47So we will explore no each of those
0:50routes no and how to calculate things
0:52there. Okay.
0:55So for this chapter outline, we would
0:57talk about the mole molar mass of
1:00compounds composition calculating
1:03empirical formulas and calculating the
1:06molecular formula from the empirical no?
1:09Okay.
1:11So what is the mole? Ano ba iyung mole?
1:14No okay so mole is
1:18individual atoms that are tiny have such
1:21a small mass more convenient units for
1:26atoms are needed to be useful on the
1:28macroscale. No. So ah iyung mole po no,
1:33we can uh see this the value iyung
1:36atomic mass unit and molecular weight no
1:40pwedeng ma-calculate iyung amount ng
1:42substance no using those. Okay analogy
1:47no? Fruit in a supermarket is counted by
1:50weighing the mass of fruit.
1:54If the average mass of a for a piece of
1:57root is known, the number of piece of
2:00root can be calculated, no? So ginawa
2:04niya ng um analogy no and definition
2:09yan. So
2:12okay in this
2:13example if one orange has a mass of 186
2:18gr then 75 orange have
2:22what mass no ayan
2:25so gaano daw kalaki no yung ah
2:29weighing or timbang nung 75 orange no so
2:33ito yung ano niya
2:35um conversion factor no
2:39ito yung standard niya no one orange has
2:42a mass of 186 gr. So
2:4775 orange would be around no ah 13 950
2:52gr or 13.95 kg. Okay.
2:58Ah since ano 'to? Since oranges 'to
3:00pwedeng hindi ito no. Hindi exactly this
3:03uh way no kasi some oranges would be
3:06bigaker no some oranges would be smaller
3:09no. Ah sa chemistry no we also use the
3:12same no concept.
3:15Chemis counts atoms no in a similar way
3:19by weighing it. So ang hinahanap natin
3:22is yung atomic mass unit or yung um
3:29what you call this molar massung
3:31hinahanap natin.
3:33Okay. Now often we use the unit grams
3:38per
3:40mole dito.
3:43Okay.
3:46Ayan.
3:48So units of measurement pinapakita lang.
3:52Eggs are measured by dozen. Paper is
3:55measured per rim, no? Per cluster nung
3:58paper. Pencils are measured by the
4:01gross. I ano niya containment niya, no?
4:04Okay.
4:06So,
4:08okay. This is the abogadros number.
4:121 mole is equal no to 6.2
4:186.022
4:2010 23 no power
4:24object.
4:27So itong object na to no can be
4:30particles
4:32no can be subatomic particles no etc.
4:35Yan the number presented by 1 mole.
4:40Okay. Ito which is the Avogadros number.
4:43Such a large number is useful because
4:46even the smallest amount of matter
4:49contains extremely large numbers of
4:51atom.
4:55Okay. Mole is similar to other common
4:58units of counting. One dozen etc.
5:06Moles can be used to describe elements,
5:10particles or compounds. So pwedeng
5:12maging atoms,
5:14molecules,
5:17electrons, yung subatomic particles and
5:19so on. No, ayan. So yun yung concept
5:23nung mole, no? Ayan.
5:27Then saan naka-base ong number na to?
5:30Ano? Yun was provided by Avogadro. Okay.
5:39Ayan. So
5:41Avogadros number can be used as
5:43conversion factor. Ito po siya. Yan.
5:50Okay.
5:51So if you're given number of atoms,
5:56number of molecules
5:59yan or electrons or protons,
6:02we can use the Avogadros number, no to
6:05convert it to
6:08mole. If you're given mole, we can use
6:11it to convert into Avogadros number,
6:15yung objects, no? Ayan.
6:18Um, fix po ba yung yung number na to?
6:22Yan. Fix po ba y'yan?
6:26What's your answer class? Is it fixed
6:28based on your genem?
6:33Oh yes. Ah this one is constant no? Yan.
6:36Basta lagi siyang ganun ha. Yang 6.022
6:4210 to the 23d
6:45over mole. No'no, lagi siyang gann
6:48no'no. Okay. Now, yung word na object
6:51diyan can be atom, can be molecules, can
6:55be electrons, can be particles, etc. No
7:00ganon.
7:01Okay po ba?
7:03Ayan.
7:08How does the mole relate to masses of
7:11elements? Ayan na. Okay. So ang sabi
7:14dito, one mole of any element is defined
7:18as the amount of that substance that
7:20contains the same number.
7:26Nakato. Same number of particles as
7:30exactly 12 grams, no? Ayan.
7:33So 1 mole of n any element contains same
7:37number of atoms but teka can vary
7:40greatly in overall mass. Ayan teka. Okay
7:44so do 12 quarters way the same as 12
7:47times. Sige na without ano
7:51puntahan natin yung molar mass.
7:55Okay. So
7:58how do we calculate no molar mass? Yan.
8:02So very ano naman to very elementary no?
8:06So
8:08okay so we have here 40.08
8:11g. Okay so iyung ah 1 mole of calcium no
8:17is equivalent to 40.08
8:22gr.
8:23Ah saan nanggaling itong value na to?
8:26No? Where did we obtain this value? So
8:29you can you can uh determine no or pwede
8:32niyong mahanap yung value na to with
8:34your periodic
8:39table. It is written there no? Yan.
8:44Then um for florine you have 19 grams no
8:50since you have um a calcium and two
8:54florine.
8:57Okay?
8:58Ayan. So kung dalawa yung florine mo,
9:00you have to multiply the the 19 no with
9:04number
9:06two. Indicating that you have two atoms
9:09of florine, no'.
9:13Ayun. So pag in-ad in-add mo lahat yan,
9:15okay? You have 78.08.
9:19We call this molar
9:24mass. Okay.
9:28Okay. Ayun. Another name no? Molecular
9:30weight. Also known as molecular weight.
9:36Ayan.
9:38Okay. So don't get confused. Ah. M
9:42terminology lang naman yan. Molar mass
9:44or molecular weight.
9:48Ayan. Okay.
9:52So
9:55ayan. Molar mass in the lab. Ayan. So
9:59ayan po 32.07
10:01gr that's equivalent to
10:056.022 0 to2 * 10 23 no atoms. Bakit?
10:11Kasi ang 1 mole
10:15ng sulfur is 32.7 gr. Yung 1 mole kasi
10:20equivalent daw dito no? With iodine the
10:24same, no? So yung 1 mole niya.
10:27Tapos ito
10:30sa iron ganun din 1 mole.
10:33Mercury 1 mole. Yan equal to this no? So
10:38ibig sabihin po yung
10:41ah
10:431 mole
10:45ng bawat element
10:47no iba-iba sila in terms of
10:51mass dito nagkakaroon ng
10:54variation.
10:56Gets po ba? And
10:59where can you get the molar mass? Again,
11:02you have to use the periodic
11:07table ba? Okay. Sige nga. Do you have
11:11your periodic table right now?
11:20Okay. Do you have your periodic table
11:22right now? Meron.
11:24Okay, sige game tayo. [tawanan]
11:27[sumisinghap]
11:28Okay. Um,
11:30tekaisip
11:32ako ha. [tawanan]
11:34[sumisinghap]
11:35Oh, what's
11:38how many mass no for 1 mole of yan?
11:44Magnesium. Sige ah chinat ko chinat ko
11:48guys.
11:59Okay. Ayun. So nasa ano 24 po. Ayan.
12:03Unang nakasagot si Miss Magsino. Ayan.
12:07Okay. So nakita niyo no? Nasa periodic
12:11table sila nakasulat doun ha. Tapos uh
12:15we often use the unit grams per mole.
12:21Gets po ba? So kung yung magnesium is
12:2424, so nakalagay diyan is 24
12:27gr per mole. Anong ibig sabihin no? Ibig
12:30sabihin sa 24 gr
12:34ng magnesium ang equivalent daw po niya
12:37is 1 mole of
12:41magnesium. Okay. So ganun lang no? So
12:45basically yung
12:48mole it represents no how many atoms how
12:52many of this and that no atoms
12:55yun yun nga lang ang bawat atom
12:56nagiiba-iba ng mass no ayun ang bawat
13:00element rather.
13:03Okayan.
13:05Now, okay. Sige nga. Example, we convert
13:09no moles of lead.
13:13How many moles of lead does 15 grams of
13:17uh
13:18yan lead have? Ayan, ito yyung solution
13:21map.
13:22So we use okay no this is our conversion
13:27factor.
13:29So if you're given 15 grams
13:34lead.
13:36Okay? So gamitin natin ng ano
13:39dimensional analysis.
13:41So I have to place no uh on top
13:471 mole
13:51and then at the bottom 207.2
13:55two crems
13:57lead. Okay.
14:00What's the logic? Why did we choose a
14:05versus B? Bakit ito yung pinili nating
14:06conversion factor, guys?
14:09What's the logic?
14:11Anong dahilan? Bakit yun ang pinili
14:13natin? Yung yung itsura. Okay. To
14:16cancel. Correct. Okay. To show us no,
14:20how we cancel grams. Ito maka-cancel
14:23kasi 'to no'.
14:25Yan. So maka-cancel sila. So ano
14:27magiging ending end unit natin no? So we
14:30would have
14:33ito ano yan moles pb. Yan yung magiging
14:37end unit natin ' ba? Mole PB tandaan ha.
14:42Ganun lang siya guys ha. Again saan
14:46mahahanap 'to? Periodic
14:50table ha. So ibig sabihin during your
14:54exam it would be essential for you to
14:56have periodic table. Hindi pwedeng wala
15:00kayo non ha. Okay? Mahihirapan kayo.
15:04Okay? Mag-exam.
15:08Maliwanag po?
15:11Okay. Sige next natin yan. So okay ang
15:15naging sagot natin okay for that is
15:20o no 7.24
15:23* 10 to -2 ra -2 moleed
15:30no PB. Ayan
15:34okay o sige nga yan o.
15:39Oh paunahan ulit. Sino una makasagot?
15:43B.
15:44Okay.
15:49Okay. Bakit B? No. How many moles of
15:52mercury does 23 grams? No.
15:57Teka. Okay. Of HG represent. Okay. Ang
16:01sagot niyo ay B.
16:05Ay, parang bumalik. Ayan. So yung uh
16:09conversion factor daw that we use. Okay.
16:13O no.
16:16Okay. Pero what we need is this format.
16:19Itong itsura na to no yun yung nilagay
16:22natin doon to get
16:25o ano.
16:32Ayan.
16:33Okay.
16:35Oh. What about ito naman oh.
16:38Uh how how many atoms? Atoms naman ang
16:41tinatanong ha. Hindi mo?
16:47Of 16 grams of AU no? Okay. So ang
16:51binigay dito is yung molecular weight
16:53niya. Ito and yung ah conversion factor
16:58with Avogadros number ba. So how do we
17:02write this? Sulat natin. Sige. So 160
17:09gr
17:12gold.
17:16Okay. So we have 1 mole
17:20AU
17:22197.0
17:24g.
17:31and then multiply again no?
17:34Multiply again. Okay. 6.022
17:40* 10 23d
17:45atoms
17:47of gold. No yan over 1 mole
17:53AU.
17:57Ayan. So tingnan natin class. Tingnan
17:59niyo um
18:03what's the reason 'n bakit ito 'yung
18:04pinili nating conversion factor? You
18:06would see that uh grams cancelled
18:11cancelled. No it kita niyo
18:16t saka ito no.
18:18These two would cancel each other. Kita
18:22oh. Ito rin maka-cancel kasi ito ' ba.
18:26So the only unit no you would be left
18:29with no is this unit. Ito atoms
18:35AU or our room no gold. Ayan kita.
18:41Okay. So
18:43answer would be
18:484.89 * 10 ra 22. atoms
18:55no gold yan
19:01okay mm
19:04oh try nga oh
19:07ti
19:11o anong sagot niyo guys
19:15letter c okay
19:18si missiego yung nauna okay so ito yung
19:21sagot
19:24Tingnan nga natin kung ito.
19:29Okay. So yung sagot is
19:35okay. Ah see no. Ito how we came up with
19:38that answer. No ah ito po yung solution.
19:45Yan.
19:49Okay. So basically
19:51ah anong ginamit nating conversion
19:54factors? Ito isa
19:58dalawa. Ayan. So this one is the
20:01avogadros
20:06aogadros number. And then this one this
20:09is the atomic mass unit or the molar
20:16mass
20:18written in where no? Again, ito ay
20:20mahahanap sa periodic table ha. Ito
20:24constant
20:26lagi siyang 6.202
20:2910 to 23 over 1 mole. No?
20:38Ayan.
20:41Oh, what is the mass? Okay. Ah, lithium
20:44naman 'to no'.
20:46O, paano naman kung pabaliktad guys?
20:49Halimbawa, you were given the number of
20:53atoms or lithium.
20:57How would you write no this uh
21:02equation or calculate this no? So
21:06meron kang 2.13
21:1010
21:12to the 18
21:14atoms
21:17lithium. No? So first
21:20you have to convert this, no? So
21:23ico-convert muna natin siya from uh
21:25atoms
21:27going to mole and then going to
21:32ah grams or
21:35mass, no? Ayun. So ito yung magiging ano
21:39natin um solution map no for this one.
21:46Okay. So ang sabi forever 1 mole
21:51lithium
21:536.022 0 22
21:5723
21:59atoms lithium
22:02multiplied
22:04okay
22:07so
22:10take note of this tingnan niyo mabuti.
22:12Ang 1 mole daw ng lithium is 6.941 941
22:16grams
22:18since we are looking for uh the mass no
22:23instead of writing this way tingan
22:26niyong mabuti. Okay? So ilalagay natin
22:29yung 6.941
22:33grams of lithium
22:37okay and 1 mole
22:42lithium. Ayan you would notice class
22:46tignan niyo mabuti ha
22:49atoms lithium would cancel ba
22:54dito no magka-cancel sila and then this
22:56one would also cancel kita plus ah when
23:03computing
23:05no ah pag sinabi sa problem halimbawa
23:09dito ang pinapahanap sayo mas
23:12look at the unit It's how they would
23:14play or how they would cancel. Lagi
23:17niyong babantayan yung units. If mas ang
23:19pinapahanap, make sure that you won't
23:22you won't give an answer in halimbawa
23:25mole, no? O kaya atoms, no? Maliwanag?
23:30Plus class?
23:32Naintindihan? [sumisingasing]
23:36Okay.
23:40Ayun ha. Basta babantayan niyo lagi yung
23:42units. Kung ang hinihingi ay mass, mass
23:44ang ibibigay mo. Kung ang hinihingi ay
23:46mole, mole ang ibibigay mo. Kung atoms
23:50or particles or molecules or avogadros
23:53number na yung sagot na hinihingi is yun
23:57yung ibibigay mo no? Now, yung mga
24:00conversion factor plus ito no yan they
24:05can be written no' uh
24:08inverse no. So for example itong 6.022
24:1510 to 23d pwedeng ilagay sa taas tapos
24:18yung mole pwedeng ilagay sa baba no?
24:21Okay? Pagpapalitan mo ng pwesto depende
24:24sa need mo no? These are conversion
24:26factors kasi no. Ayan equivalence no.
24:31Okay.
24:33Ayan.
24:35So
24:37ayan.
24:38So ito daw yung sagot natin
24:41oh. 'Di ba?
24:43Atoms.
24:45Okay. Cancelled. Cancelled. Moles.
24:47Cancelled. Cancelled. You will be left
24:50with ayan grams and lithium na unit no.
24:58Okay. O sige try.
25:01Oh,
25:03from atoms to grams.
25:09Okay. A ba? O sige
25:16oh. Tingnan natin
25:20o yan no. So dito no uh atoms yung
25:24binigay sa atin plus ah yung map natin
25:28is hindi ka pwede mag-convert ng atoms
25:33no or Avogadro no number
25:38diretso
25:40sa grams or sa mas hindi to pwede. Okay
25:47teka lagyan ko ng X yan hindi siya
25:50pwede. So ang pwedeng route natin is
25:55atoms
25:57going to moles
25:59going to mass. No, ito yung tamang
26:04route. Okay. Ayan. So we were given no
26:09conversion factors. One for neon molar
26:13mass another is the avogadros number
26:17which is yun naman yun ' ba. Okay. So,
26:20first we convert the Avogadros number or
26:23the atoms into mole
26:26and then we use the molar mass of the
26:29neon to convert it no to mass.
26:35So the correct answer is a no? Ayan.
26:43O. O na.
26:45What is the mass of 1.05
26:49moles silver?
26:52Okay.
26:53Ito yung conversion factor.
26:57O sige nga. Can you type the answer
27:00for this one?
27:05Try convert this. Convert the mole into
27:08grams.
27:17Okay. So 113.3
27:22no grams of silver.
27:26Yun no? Okay.
27:29So ganun siya no?
27:42Okay. Ah converting moles of potassium.
27:46A practice daw. Sige.
27:50Mas maganda sana kung face to face to eh
27:52no para ano may hawak talaga kayong
27:55calculator. O anyway sige na.
28:01Tapos may ano pwede akong magpa-seat
28:03work sa inyo, no? [tawanan] Okay.
28:07So tama no? Letter A yan.
28:12Sige-check natin o ito yung solution no.
28:16So the answer is a. Okay. Why no? Um you
28:21have 8.21.
28:23Um
28:25okay you have t1
28:30moles of potassium.
28:32Saan nakuha to class? O tandaan ha. Saan
28:36saan kukunin ong ganitong value?
28:38Periodic
28:40table. Walang katapusang periodic table
28:44ha.
28:45Okay. Habang nag-aaral kayo ng chem,
28:49madalas gagamitin yan no? Ayan.
28:53Okay. Kahit anong klaseng chem pa yan,
28:56physical chemistry, organic chemistry,
28:58analytical chem, biochem, you would
29:01still refer to your periodic table.
29:04Bakit? Kasi
29:07elements are always involved no' in
29:09chemistry. Ayan. So, and 'yung bawat
29:13element, they have their own molar mass,
29:16'no? 'Yan. Elemental pa lang 'to. Wala
29:19pa tayong compounds, 'no? Okay.
29:25Ayan. So,
29:30okay. Um,
29:32ayan.
29:34How many hydrogen atoms are in 1 mole?
29:37Okay, so 1 mole naman daw. Ilang atoms
29:40daw no?
29:42Ayan.
29:46Okay.
29:49Ah so how did we calculate it? No okay
29:54so ang ginawa dito
29:56teka moles of H2. Teka take note. H2
30:01molecules of H2
30:04and then atoms of hydrogen. Teka.
30:09Napansin niyo yung difference?
30:11So from H2
30:14no na yun yung given.
30:17Okay. So diatomic hydrogen ang
30:21pinapahanap sa atin is
30:25okay atoms of hydrogen
30:30H lang no? Okay. So ang binigay sa ating
30:33conversion factors ito.
30:36Teka baguhin ko 'yung color. Wait lang.
30:39Ito
30:41and ito no. Ayan.
30:45So ang one molecule ng
30:50diatomic no hydrogen ayan na.
30:53Okay. Is
30:55two atoms
30:57H kita.
30:59So 1 mole
31:03um hydrogen gas
31:06times no 6.022
31:09to the 23d molecules H2 yan over 1 mole.
31:15So makukuha natin yung
31:17mo in molecule no yan. And then this
31:21unit would cancel this unit. Ito to. So
31:26you would be left with two atoms
31:30yan hydrogen tos imu-multiply mo yan
31:33diyan and then ito na no
31:37ayan okay
31:45okay ayan so why is there a need no to
31:49get no kasi atoms lang naman e
31:51pinapahanap hindi molecule no ayan
31:56Teka sige nga try natin 'to.
32:01O
32:02how many sulfur atoms?
32:05Okay. In 20 ah 2.27
32:11no? Mole of S8.
32:15Try natin. Try. Susulat ko ha. Papaano?
32:17Ito 2
32:2027 mole.
32:25S8.
32:30Okay. So 6.022
32:34* 10 23.
32:39Okay. Ah ano muna to?
32:48Molecules.
32:52Teka.
32:57S8.
33:02Okay. Tapos 1 mole no?
33:06S8.
33:08And then
33:13okay tapos ang meron tayo is
33:191 mole
33:22molecule pala. Okay. S8 8
33:27tama ba? Atoms eh. Ayan
33:31atoms no?
33:35S. Ayan.
33:38Okay. So ito yung tingin ko na working
33:40equation. Sige. So cancel to. Dapat
33:45ka-cancel yung molecules dito. So we
33:48would be uh left with atoms no of S8.
33:53Ayan try nga natin.
33:56So ayun.
33:59Tama ba? Same no?
34:04Okay.
34:07Teka.
34:11So saan napunta 'to?
34:14Ayan.
34:19How many? Wait lang class ha. Teka.
34:23So solution map moles of S8.
34:27Ah ito 'yun. then molecules and then
34:30atoms no?
34:32Okay. Two conversion factors are needed.
34:35Ito and then this one no. Ayan. So ito
34:41um this one is the Avogadros.
34:43Okay. Ito naman paano nakuha 'to no'
34:46kasi dun sa
34:49S8 no yan na sulfure. Okay? So you have
34:54eight atoms
34:57of sulphur
35:00no in one molecule
35:06of
35:09S8.
35:11Okay. Pero okay bakit bakit bakit bakit
35:15bakit niya to nilagay dito no?
35:19Ah pwede namang ito na no. Ayun.
35:23So
35:26hala hindi niyo pinakita yung sagot.
35:27Teka nga.
35:31Okay. Ayan.
35:36Hmm. Bakit ito lang no? Ah okay. Sinabi
35:39niya C.
35:45Medyo problematic yata to class no? Kasi
35:48tingan niyo ha. How many sulfur atoms
35:52are in 2.27 mole? No ito.
35:57Pero d sa kinalculate niya ito no. Ayan.
36:00Balik tayo sa question.
36:04Ah tama nga. Mm.
36:10Ah okay. So dine-clear ni sagot is C.
36:15O pero yun ay nilagay niya dito
36:191 mole lang no? Ayan medyo i-double
36:23check ko 'to ha.
36:25Okay.
36:30Okay. Uh molar mass of compounds. No,
36:33much like an element, molar mass can be
36:35defined for a compound. So pwede rin daw
36:37gamitin no ah kung pwedeng gamitin sa
36:41element pwede ring gamitin sa compound.
36:43Okay? Mass of 1 mole of a of the formula
36:47unit of a compound. No ayan.
36:52So for example no
36:55water.
36:57Okay. So ' ba ang ginagawa natin dito no
37:01nung ah
37:03basic education ' ba H2O
37:07ginagawa nilalagyan ng line sa ilalim.
37:11For example no 1 gr per mole
37:16we multiply it by two no? So you would
37:18have 2 grams per mole.
37:22And then for the oxygen you have 16 gr
37:26per mole times 1 no 16 gr per mole
37:3318 gr
37:39okay 18 gr mole yung total no yan ah
37:43sino sa inyo naka-experience ng ganito
37:46no yung nilalagyan ng line
37:49ayan so who among you haveed ah tried or
37:52experience no yung nilalagyan ng line na
37:54ganyan ano so you can you can still do
37:57that no as long as you would land on the
38:00same answer no pero you can just uh get
38:04the atomic mass unit of each element
38:07multiplied to how many atoms no we have
38:10in a compound no ayun
38:14Okay.
38:20Mhm. O sige nga ito try nga.
38:24Okay. Aluminum hydroxide. Ayan.
38:29So how many aluminum do we have?
38:32Isa lang no oxygen. If you
38:37use the subscript no d sa labas ng
38:41parenthesis you would have 3. For the
38:44hydrogen you would have 3.
38:48Sige nga. What's the
38:50molar mass?
38:54Okay. So ang sagot
38:56B. Okay. Bakit B?
39:00O sige try natin. Ayan. So ang sabi dito
39:04no, for everyone aluminum no mole of
39:09aluminum
39:11you have 26.98
39:15for every oxygen 16 for every hydrogen
39:18is 1.008.
39:20No'no since you have uh three oxygen,
39:25three hydrogen, you have to multiply it
39:28by three. And then 'ag nakuha mo na 'no
39:32ito na-multiply mo na, you would add
39:36all. Hence, you would get the molar mass
39:40of this
39:42compound. Gets? Okay.
39:46So gan lang siya, no? Ayan.
39:53Okay. Um, molar mass of a compound
39:57contains avogadro number of formula
40:00units molecule. No, ayan. So,
40:07okay.
40:11Ayan. So dito no,
40:14H2 sa dalawa. So yung ah 6.20 22 10 23
40:22is actually equivalent to 2 no? Ayan so
40:262 moles of hydrogen so therefore 2 times
40:301.008
40:32okay kasi um ang sinasabi dito no kung
40:36sa case ni hydrogen
40:39yung 1.008
40:42grams equal siya sa 1 mole
40:47of hydrogen. Tapos ito daw ay equal din.
40:50Itong 1 mole is equ 0.22
40:5510
40:57to the 23d. No? Ayan.
41:01Okay. So pay close attention to whether
41:06the desired unit involves atoms
41:10or formula units over molecule. No?
41:14Example
41:16contains 2 moles of chlorine atoms but
41:20only 1 mole
41:23of chlorine gas no molecules. Ayan.
41:29So medyo confusing kasi no. Um babasahin
41:33niyong mabuti yung problem ha. Cless if
41:35it is asking for uh 1 mole of chlorine
41:40gas.
41:42Atoms ba yung tinatanong? Is it
41:44molecule? No, ayun. Don't worry. Ah,
41:47yung mga questions natin will make it
41:49more um
41:52easier no to comprehend kung ano yung
41:54hinihingi no. Okay. Nasa paggawa kasi ng
41:59tanong yan eh no? To avoid confusion.
42:02Dapat kasi yung questions din is ano
42:04hindi siya confusing no?
42:08Okay.
42:11Ayan. Okay. So molar mass as a
42:14conversion factor. Can we use molar mass
42:18as a conversion factor? So
42:21okay the answer is yes. Pwede. No for
42:25example last
42:27you have a grams of sodium chloride.
42:31Okay. So you can use the molar mass of
42:34sodium chloride no to convert it to
42:37moles of sodium chloride.
42:40Okay? Ayan.
42:44Ayan. So ang molar mass daw ng sodium
42:46chloride is 58.44
42:49gr. Ayan.
42:54Okay. So you were given 253 gr of sodium
42:57chloride. Ito yung ating conversion
43:01factor. Ito yung amount ng mole. Okay.
43:13Conversions using molar mass.
43:18Okay. Practice. Sige nga. How many moles
43:22of uh titanium chloride?
43:31Oh, are there in 12.5?
43:34Sige.
43:38Ah. Okay. Okay. Sige try natin.
43:42So the answer is A. For the solution
43:45map, ito no. Ah.
43:49Okay, this is how we obtain the molar
43:51mass or the molecular weight no of your
43:53titanium chloride, titanium 4 chloride,
43:56no? Okay. So, ito, ito daw yung timbang
44:01ng isang titanium, 1 mole of titanium.
44:05Ito naman daw yung mass ng isang
44:07chlorine 35.45. Since you have four, ito
44:11yun no?
44:13So, yung molar mass ng titanium chloride
44:16is 189.7. 7 grams.
44:20So
44:21basically no
44:24ah 189.7 gr per mole per mole to ha yan
44:34okay so
44:37ayan 12.5 gr titanium chloride
44:411 mole titanium chloride over 189.7 7
44:46titanium chloride you have to cancel
44:48this unit no
44:51okay so we get 0.0659 0659
44:54moles
44:56of titanium chloride no?
45:06Okay. What is the mass of 3.45
45:10moles of lithium oxide?
45:16Sige nga. Okay. Ayan na. [tawanan]
45:21Okay. 103
45:23grams no lithium oxide. So the same
45:25principle was uh
45:29provided no class
45:32okay marunong bang kumuha ng molar mass
45:36ng isang compound?
45:38Pataas naman ng thumbs up naman kung
45:41marunong. Kung hindi, ibig sabihin
45:44kailangan pa ng practice para alam ko
45:46ha.
45:48Marunong kayang kumuha ng molar mas?
45:54Hindi pa. Sige. Ah mamaya mag-iiwan ako
45:58ng pwede niyong pag-practicean ha. It's
46:01a seat work via LMS.
46:04You practice. Okay.
46:07So
46:09yung sa LMS mamaya no um
46:13you you have to use the periodic table
46:15no. Okay. So, papaano ba kumuha ng molar
46:19mass no? Teka, sige. Nagla-log yung
46:24aking mouse. Ayan. So, for example, no,
46:27lithium
46:31two
46:33oxide.
46:35So, ang ibig sabihin nito no, lithium 2
46:38oxide, you have two.
46:41Oops, nagla-log
46:44yan.
46:45lithium and one
46:49oxygen sa periodic table mo no ang isang
46:53oxygen kasi is 16
46:56grams per
46:59okay mo mol mole ayan tapos ang isang
47:05lithium okay
47:08oh teka wala akong hawak na periodic
47:10table eh ano bang ano ano bang
47:14Ah, molar mass. Walang time limit iyung
47:17seatwork. Yes. Oo.
47:20Ay, ito pala. Inabutan na ako ng
47:21periodic table. [tawanan]
47:24Okay. Ang periodic sa periodic table
47:26natin na nakalagay diyan is 6
47:3093.
47:32Tama ba? Yun ba ang yun ba yung sa
47:35lithium 6.93? 93 pareho ba kayo na
47:38nababa?
47:48Ayun. So yung iba 6
47:5294 naka-round off na siguro yung sao no?
47:56Kasi ah
47:596.938
48:01yung nakalagay no.
48:04Ayan. Tapos may isa pa siyang ano ah
48:07naka-end no. May ganitong symbol.
48:11Ayan. So
48:14may isa siyang isotope no na 6.997.
48:21Ayan. So sige.
48:24Ayan. 6.9 9 ah 38 yung gamitin natin.
48:28Okay. So for every lithium
48:346.93.
48:36Teka nagla-log yung mouse. 8
48:41grams
48:43per
48:46mole. No? Ayan
48:48eh. dalawang lithium 'yung meron ka 'di
48:51ba? Ito para sa isang lithium pa lang
48:53'to. So ibig sabihin itong value na to
48:56you have to multiply this by two. So
48:59ibig sabihin teka type ko na lang
49:04no. Ayan. So ito yung ginawa niya. Ito
49:07yung ah galing ng periodic table.
49:11Okay. Ito rin galing ng periodic table
49:14to.
49:19Yan minultiply sa two ah kasi dalawang
49:23lithium and then pinag-add
49:26o ito na ito yung molecular
49:29weight or molar mass no ayan
49:37okay
49:39so ibig sabihin no ito ipe-prepare mo
49:42muna to no before you could convert
49:45birth.
49:47Okay. Ayan.
49:56Oh.
49:59Oh. Sige nga. Ito nga. Try.
50:07Okay. So try natin. Ah
50:12okay. Ano ba ang lagay ko dito? Ang
50:16phosphorus mo.
50:18Okay. That's 30 point
50:2397 gr per mole. Ang hydrogen is 1.008 gr
50:29per mole.
50:31Yan. kita.
50:33So ibig sabihin
50:38for the phosphorus
50:40okay you need 30.97 97
50:43grams per mole ah times 1 lang kasi you
50:46have one phosphorus na no
50:507 gr per mole teka lagay natin diyan
50:56yan tapos sa hydrogen you have
51:00grams per mole times ah ilan ba no ayan
51:07teka paghiwalayin ko para mas kita niyo
51:10ng maayos
51:13Okay, teka
51:18wait lang class ha.
51:201 point
51:24so that should be 3.024
51:27grams per.
51:30Okay. So ang total niyan plus 30 point
51:42okay
51:45yan. So ang total nito no total ilalagay
51:48ko dito
51:55is 33.994.
51:57994 grams per mole. Ito y'yung ano, ito
52:01na yung
52:13yan.
52:15Okay.
52:16Ayan.
52:18So ito na siya no. Ayan. Kita niyo guys
52:23oh. Ah bakit? Ano? Bakit? Ah
52:30okay. Saan saan nakuha? Onong one? Saan
52:32nakuha?
52:35Tingnan mabuti ha. Isa lang ang
52:37posporus.
52:39Bakit may three? Okay.
52:44Tatlo yung hydrogen.
52:48Saan nakuha itong mga value nito?
52:53Sa periodic table.
52:57Ayan.
53:00Gets na ba? Gets anong tawag dito?
53:04Okay.
53:06Anong tawag diyan? Okay.
53:12Oh,
53:13yon. Correct. Okay. [tawanan]
53:18Ayan. Naintindihan ha? Naintindihan?
53:19Na-gets niyo yung logic?
53:24Okay ha? Naintindihan kung saan
53:25nanggaling 'yung mga numero ha. Okay. So
53:29lahat yan may basis ha. Hindi pwedeng
53:31manghuhula ka. Okay.
53:34So tandaan itong mga value na nakapula
53:37kukunin mo sa periodic table.
53:41Yung number na blue na inunderline ko
53:44galing yun sa chemical formula.
53:48Would serve as multiplier
53:51ba? Ayan.
53:53Pag tinotal mo sila minultiply mo at
53:55tinotal mo na. lahat-lahat
53:59yan. So magkakaroon ka ng tinatawag na
54:03molar mass no.
54:07Okay then yung molar mass, anong klase
54:09ang molar mass? It's a conversion
54:11factor, no? You can use it to convert ah
54:15moles to grams, grams to moles, ha.
54:19[sumisinghap]
54:20Okay. So sige.
54:22So our answer for this it ano? Bakit?
54:27Kasi yung 1 point
54:31Teka pakita ko na.
54:35Okay? Kasi yung 1.23
54:38Okay. Ito siya. Okay. Ito yung ginamit
54:42natin na
54:44ah molar mass. Ayan.
54:48Okay. So, maka-cancel po yung moles and
54:51then you would be left with yan grams.
54:56Okay.
55:00Ah, mamaya after nitong discussion natin
55:02ha, I would provide you seat work via
55:06LMS.
55:08Okay. Then afterwards nasagutan niyo na
55:11I would provide the answer key. Okay? So
55:13para ma-counter check niyo kung tama
55:15yung ginawa niyo. Okay?
55:20Okay ba yun? Para may ano tayo, may
55:21practice tayo ha bago yung exam. Kasi
55:24next na magkikita tayo, it would be
55:26another Saturday tapos magla-lab pa
55:29tayo. Supposedly dapat nakapag-practice
55:31kayo nito eh. Ngayon sana yun eh. Kaso
55:35wala. [tawanan]
55:38or ngayon yung love, next week yung
55:39practice. Pero anyway, sige na.
55:44Ah hindi natin control yung weather eh
55:47no. Okay. So
55:51okay. How many molecules of H2S
55:55present in
55:577.53 gr of H2S? No. Ayan.
56:03So how do we convert it no? Ayan first
56:08no.
56:09Okay. Ito kasi naka grams. Kailangan
56:13ma-convert muna natin siya in
56:17moles.
56:19Okayan.
56:21Convert mo muna sa moles.
56:24Afterwards, you can now convert it to
56:28Okay. Molecules.
56:33Teka nga.
56:35Molecules.
56:46Ayan. Nagla-log yung mouse ko. Sorry.
56:48Ayan.
56:50Don't get confused ha. 'yung mole. Okay?
56:54Ah ito yung kinukuha no or ito yung
56:56makukuha using molecular weight or molar
56:58mass. Ito naman, ito yung kinukuha or
57:01makukuha gamit ang avogadros number ha.
57:05Magkaiba sila ha yang mole and molecules
57:08no?
57:10Ayan. So ito yung
57:12solution.
57:14So we have 1.33
57:1710 to 23 power molecules H2S.
57:26Ayan.
57:28Okay. So, how many uh atoms of uh
57:33hydrogen? No, pag tinanong kayo how many
57:35atoms? So, basically no um diyan kasi
57:40sa molecule na to no meron tayong ah two
57:44atoms
57:47ng hydrogen.
57:53Ayan. So ang ginawa no, two atoms of
57:55hydrogen over one molecule of H2S. Yan.
58:00So if you're ask kung ah how many atoms
58:04of hydrogen ito po yan.
58:10Okay. Okay.
58:15Sige. Yan. Molar mass of H2O2.
58:20Yan. Ah.
58:22Okay. Molecules of H2O2 are there in
58:250.759.
58:28So again, ang solution map natin grams
58:34to moles. No teka ko na nga lang. Grams
58:39to moles to
58:42molecules. Yun pa rin yung route natin
58:44no. Ayan, ganyan pa rin.
58:51Okay yan. So
58:56yan po no. So 1.34 * 10 to 23 molecules
59:01H2O2.
59:03Okay. Percent composition.
59:06Okay.
59:08Uh can we also get percentage no?
59:12Percent mass of each element.
59:15in a compound no ilang percent
59:20okay a molar mass is equivalent no to
59:23100%
59:24per composition is independent of sample
59:27size.
59:30Okay.
59:32Ayan. So composition can be determined
59:36by one knowing the compounds formula to
59:40experimental data. No
59:44ayan. So calculate the molar mass of a
59:47compound percent of element.
59:50Yan total mass of the element
59:53um compound molar mass no times 100.
59:57Yan. So ano paano bang example nito?
59:59Sige nga.
1:00:04Calculate compound molar mass. Ayan. So
1:00:07ang una munang ginawa no to calculate
1:00:09the composition of K2S.
1:00:12Okay? Ang una muna daw ginawa is alamin
1:00:15yung molar mass mismo nung K2S. Okay.
1:00:22Okay. Now, um
1:00:25yan ilang per ang potassium no? In that
1:00:30ito yung molar mass niya.
1:00:32Notice yun yung ginamit natin as
1:00:36denominator.
1:00:38Eh saan galing to no? Okay. Ito yung
1:00:42amount ng potassium
1:00:44in this
1:00:48molar mass ' ba. So may dalawa ka kasing
1:00:51potassium. Ito yun. Dalawa 2.
1:00:55And sa bawat ah mole ng potassium meron
1:00:59kang 39.10 10 grams.
1:01:03Ayan. So ah 39.10 * 2 / 110.3
1:01:10100 ibig sabihin sa K2S
1:01:1470% or 70 70.90%
1:01:18is potassium.
1:01:24Ayan. Okay.
1:01:28And of course since dalawa lang yung
1:01:30ano, dalawa lang yung ating um
1:01:33element diyan, kung 70.90
1:01:37no per yung potassium kahit i-minus mo
1:01:39na lang sa 100 no. So you would be left
1:01:42with 29.10%
1:01:45for sulfur no?
1:01:49Ayan.
1:01:51Okay. Pero ayan pinakita pa rin no yung
1:01:53calculation niya. So we can determine
1:01:55the percentage composition no ayan of
1:01:59elements in a compound.
1:02:02O sige nga ilang ano ilang percent ang
1:02:06oxygen?
1:02:11Mmm ' ba ang bawat ah ano'
1:02:21ah wait lang class ha. May nag-message
1:02:23sa akin.
1:02:32Ah, okay. Ayan. Okay. So, ilang percent
1:02:36ang ating ah oxygen sa H2O2?
1:02:41Tahimik na. Wala ng sumasagot.
1:02:44Ayan.
1:02:48Okay. So, bakit A? No, ayan.
1:02:52Okay. So tingnan natin kung bakit.
1:02:56Okay. 94.06%.
1:02:59Okay. Ayan. Kita niyo no?
1:03:03So ito yung kanyang molecular weight or
1:03:05molar mass.
1:03:08So 32 yung total na ano na timbang ng
1:03:12oxygen d sa H2O2.
1:03:15So you have 32/ 34.02.
1:03:21Okay. And then times 100 that's the
1:03:25percentage of oxygen
1:03:29ba.
1:03:31Ayan.
1:03:38Okay. And then ah
1:03:41percent composition of uh potassium
1:03:43chromate.
1:03:47Dichromate ba toto? Ah oo. Tama.
1:03:50Ayan o po.
1:03:54Ayan. So
1:03:57okay. So dito pinakita ilang percent ang
1:03:59potassium, ilang percent ang chromium,
1:04:01ilang percent ang oxygen. No?
1:04:09Okay. Per composition from experimental
1:04:12data.
1:04:15Calculate the mass of compound formed.
1:04:20Okay? Divide the mass of each element,
1:04:22total mass and multiply by 100. So
1:04:25papaano ba yun? No. Ayan.
1:04:29So
1:04:31okay. So sabi dito no when heated in air
1:04:361.63 gr of zinc reacts with 0.40 40 gr
1:04:40of oxygen to give uh zinc oxide.
1:04:44Calculate the composition of the
1:04:46compound formed, no? Yan. So
1:04:51okay,
1:04:53pakita ko muna pala
1:04:57yan. So sabi dito step one,
1:05:01okay, calculate the mass of the compound
1:05:03formed. No? So
1:05:08ito kasi yung meron tayo 'di ba?
1:05:11Okay. 1.63 gr of zinc with 40 g of
1:05:16oxygen. You just have to add no this
1:05:21yan.
1:05:22Samahin mo lang itong dalawa no. Then
1:05:26afterwards so you now have no ah step
1:05:31one no yung mass of the compound formed
1:05:362.03 gr of zinc oxide.
1:05:40Okay. Now, how many percent no of uh
1:05:45zincasa
1:05:47compounds? So ang ginamit kasi sa
1:05:49reaction is 1.63.
1:05:53Ayan. So, dinivide mo sa total na-form
1:05:57times 100. So ibig sabihin
1:06:00ah doun daw sa 23 point ah no sorry sa
1:06:042.03
1:06:05zinc oxide
1:06:0880% is zinc or 80.3% is zinc then 19.7%
1:06:147% is
1:06:17oxygen no? Ayan. So itong same no
1:06:22mechanic or formula no that we use,
1:06:25okay? Pwede ring gamitin sa person
1:06:27composition ng mga experimental
1:06:30data no. Ayan.
1:06:39Ayan.
1:06:40Okay. So ito no a percent composition
1:06:45okay
1:06:47of an aluminum compound. Tak nga natin.
1:06:50Aluminum chloride forms reaction
1:06:53of 13.43 gr of aluminum and 53.18 gr of
1:06:58chlorine. Yan. So what would be the
1:07:00total
1:07:03or what's what's the percentage
1:07:04composition of chlorine no? So una teka
1:07:0913.43 gr
1:07:1353.18 g
1:07:17tek
1:07:19muna natin. Ayan
1:07:28teka lang class ha. Hindi ko mai-shoot
1:07:30'yung
1:07:40Ayan. Okay. 13.43 53.18
1:07:47Okay. So dapat meron kang 66.61
1:07:5061.
1:07:58So meron ka ng 66.61 no na grams. Yun
1:08:02yung yun yung total eh. Ang pinapahanap
1:08:04sao ay percent lang ng chlorine. So
1:08:0753.18
1:08:09/
1:08:1166.61
1:08:13gram. No?
1:08:19Ayan. times 100. So you should have
1:08:32Okay.
1:08:34100
1:08:36so ang sagot mo dito is 79.83%.
1:08:42Yan. So ang tamang sagot talaga no is no
1:08:46other than but B no. 'Yan 'yung tamang
1:08:49sagot. Okay. Ayan. So ito percent
1:08:53composition of an aluminum compound 'no?
1:08:56So gann siya kina-calculate 'no?
1:09:00So hindi lang ano ah hindi lang 'yung
1:09:02standard na ano 'yung ah percent
1:09:05composition ng isang molecule no? Yun
1:09:08yung through uh the values given by the
1:09:11periodic table. So pwede rin 'yung
1:09:13experimental no uh values. Okay?
1:09:18Ayan.
1:09:22Empirical and molecular formula.
1:09:25Empirical are the smallest whole number
1:09:28ratio of atoms in a compound. Molecular
1:09:31is the actual formula of a compound.
1:09:34Represents the total number of atoms in
1:09:36in one formula unit.
1:09:41Okay, for example
1:09:46whole number multiple of empirical
1:09:49formula
1:09:51and acety
1:09:52benzene
1:09:58both have the same empirical formula
1:10:01which is ano ah
1:10:05CH or hydrocarbon no yan. So basically
1:10:11both have the same empirical formula
1:10:13iyung CH. Ito no.
1:10:19So napansin niyo ang pinagkaiba lang is
1:10:20yung number ng atom ng atoms no? Yung
1:10:24same yung kanilang empirical formula
1:10:26pero magkaiba yung kanilang molecular
1:10:28formula. Take note ha.
1:10:31Empirical formula are the smallest
1:10:34number ratio.
1:10:36Yan.
1:10:37Ito yun.
1:10:48Okay. Okay.
1:10:56So from empirical to molecular. Ayan. So
1:11:00ang ginawa lang yyung empirical
1:11:01minultiply by 2 no. So we can produce
1:11:05acetaline. And then sa benzene naman
1:11:08empirical was multiplied to 6 no
1:11:11producing benzene molecular formula.
1:11:15Okay?
1:11:20So examples of empirical and molecular.
1:11:25So again ah syempre magkaiba ang
1:11:27kanilang chemical formula. They would
1:11:29have different properties no both
1:11:34chemical and physical property no even
1:11:37if they share the same empirical
1:11:39formula.
1:11:45Okay? Compounds with the same empirical
1:11:47formula have the same percent
1:11:49composition. 'Yun pala 'yung dahilan
1:11:51kung bakit 'no. Ayan. Tingnan nyo.
1:11:55Uh 'yung
1:11:57acetiline benzene,
1:12:01you would notice that they have
1:12:04the same percentage for carbon and the
1:12:07same percentage for hydrogen.
1:12:11Then you would also notice yung kanilang
1:12:14molar mass
1:12:16multiplicable.
1:12:18So
1:12:20naka-base siya sa 13.02
1:12:23for acety minultiply by 2 for benzine
1:12:26minultiply by 6 no?
1:12:35Ayan.
1:12:38Okay.
1:12:43Calculating empirical formulas. No?
1:12:46Okay. Number one, elements present in
1:12:49compounds.
1:12:52Okay. Atomic mass of each element
1:12:56ratio
1:12:58of the combined elements. No strategy
1:13:02for calculating empirical formulas.
1:13:04Ayan.
1:13:08Okay. Special case if fractions are
1:13:09encountered multiply by a common factor
1:13:12to provide whole numbers of each
1:13:15subscript. No so we have to yan
1:13:18multiply.
1:13:25Okay.
1:13:27Ayan. So ito yung ano ha ah rules. Sige
1:13:30nga try natin.
1:13:33Okay.
1:13:35So
1:13:37sabi dito, "Calculate the empirical
1:13:39formula for a compound that contains
1:13:4211% hydrogen and 88.79%
1:13:47oxygen." No
1:13:49find the amounts of each element in 100
1:13:51gr. So pag ito daw percentage na to guys
1:13:55class pag daw binaas nain sa 100 gr so
1:14:00ibig sabihin meron tayong 11.19 gr ng
1:14:04hydrogen 88.79 gr of oxygen. Ayan
1:14:12so ibig sabihin we would have
1:14:15okay 11.10
1:14:1710 mole of hydrogen and
1:14:215.549
1:14:23mole of oxygen.
1:14:26Ayan. So kinonvert pa from grams.
1:14:28Kinonvert pa natin sa moles no.
1:14:34Okay. Convert the whole numbers by
1:14:37dividing the smallest mole. No? So ang
1:14:41ginawa natin,
1:14:46teka yan ah. Teka balik tayo para makita
1:14:50niyo.
1:14:53So ang mas mababa diyan yung 5.549
1:14:56sa oxygen kesa dun sa 11.10 mole of
1:15:00hydrogen. Mas mababa yung 5.5.
1:15:03So ang tendency yung 11.10 dinivide sa
1:15:065.5 smallest.
1:15:09So ibig sabihin we have two two
1:15:13hydrogen. May dalawa daw na hydrogen.
1:15:16Okay?
1:15:17Then yung oxygen minultiply
1:15:21sa sarili niya no na mole. So therefore,
1:15:25may isa tayong uh oxygen. So therefore,
1:15:28H [sumisingasing]
1:15:31teka nagla-log ang mouse ko. So may
1:15:34dalawa tayong
1:15:38Wait lang class. Nag-aano naggi-glitch
1:15:40na siya. Okay.
1:15:43Try ko dito.
1:15:49Ayan.
1:15:51So meron tayong two hydrogen and
1:15:55one oxygen. So therefore H2O
1:16:00O
1:16:02yun pala yung pinatutungkulan nung
1:16:05nung ah sample no.
1:16:17Okay. So the empirical formula is H2O.
1:16:21Ayan.
1:16:26Okay.
1:16:33Ayan.
1:16:36Okay. So calculating the empirical
1:16:39formula for potassium compound.
1:16:42Ayan. So try nga natin'.
1:16:45Meron bang shortcut dito guys? Meron
1:16:48bang shortcut?
1:16:54Oh
1:16:56sige nga tingnan niyong mabuti.
1:17:00Without calculating, pwede bang malaman
1:17:02agad kung alin ang sagot? Kapagka
1:17:06tinanong kayo kung ano ang empirical
1:17:08formula, no? Binigyan lang kayo ng
1:17:10percentage. Ayan.
1:17:13Okay. So itoakita pakita niyo muna yung
1:17:16ano ha. Papakita niya muna yung
1:17:18uh how it would be solved no. Okay.
1:17:22Number one again ang ginawa ah 100 gr
1:17:27no? So kinonvert muna sa grams.
1:17:29Kinonvert sa moles no yung grams. Ayan.
1:17:33Okay. Tapos ano 'yung next na step?
1:17:37Hahanapin mo 'yung pinakamababa.
1:17:40So dito ano bang pinakamababang mole
1:17:42natin dito?
1:17:46Sige nga.
1:17:51O anong pinakamababang mole natin?
1:17:56So 0 point
1:18:020.723.
1:18:04Tama
1:18:06o no? Pinakamababa.
1:18:08So ibig sabihin matic no? Matic na may
1:18:10isa agad na
1:18:13carbon.
1:18:16Ayan isa na carbon
1:18:20tapos dalawa
1:18:23na potassium. Tingnan niyo mabuti no?
1:18:25Yung ito no. Ayan.
1:18:29Pag tinimes mo to sa two, ang lalabas is
1:18:31yung value nito. So dalawa to. Tapos
1:18:34merong tatlong
1:18:37okay oxygen. Kasi pag minultiply mo to
1:18:40sa three, ung lalabas is yung value
1:18:42nito, no?
1:18:45Ayan. So ibig sabihin no ang naiisip
1:18:48nating sagot is may isang carbon, may
1:18:52dalawang potassium at may tatlong oxygen
1:18:55no. Yan yun yung nakikita nating
1:18:57empirical formula.
1:19:00Okay. So meron bang ganun diyan?
1:19:04Ayan. So meron ba
1:19:06yan? So meron no? Yung sagot natin is C
1:19:11no. Ayun. Isang carbon, dalawang
1:19:15potassium, tatlong oxygen. '
1:19:21Okay.
1:19:242 + 1 + 3 6.
1:19:28So 2 / 6.
1:19:34Ay hindi siya pwede. Okay. Ayan. So
1:19:38sige. Ayan po 'yung sagot natin ha.
1:19:41Okay. Kita
1:19:45okay so pwedeng by just looking on those
1:19:48moles no yan kahit hindi niyo na gawin
1:19:51to pwede naman siyang makita agad eh
1:19:54kung ano yung ah possible na sagot no.
1:19:59Ayan. So ito naman no.
1:20:03So calculate the empirical formula uh
1:20:06for a compound that contains
1:20:08teka hindi percentage ang binigay niya
1:20:11ang binigay niya ay
1:20:14um
1:20:17grams na or mass ' ba. So how would you
1:20:20get the percentage of this no? Okay.
1:20:26So ang gagawin okay ayan binigay na
1:20:29'yung amount.
1:20:31You simply multiply it no uh
1:20:35with their molar mass so para makuha
1:20:39yung moles no. Ayan.
1:20:42So ito na yung moles nila.
1:20:45So mas mababa yung sa iron. So ibig
1:20:48sabihin
1:20:49ito.
1:20:51Okay yung iron natin isa lang.
1:20:55Tapos you would notice na pag minultiply
1:20:58onong amount nito no itong
1:21:02ah sa iron with the dito no with the
1:21:06sulfur okay or dinivide itong itong
1:21:09amount na to ano so you would get two no
1:21:14sulfur
1:21:17teka nga
1:21:21Okay.
1:21:27Ayan. So ito no.
1:21:32Okay. So you have one. Okay. Ayun. So
1:21:37may ano pala may fraction pala dito. 1.5
1:21:40kasi yung isa no. Ayan. So
1:21:46empirical formula is Fe2 S3 no.
1:21:51Ayan.
1:21:54Okay.
1:21:59Convert the whole numbers by dividing
1:22:01the smallest mole amount.
1:22:10Okay. So to get the whole number
1:22:12multiplied by the decimal corresponding
1:22:14to the number denominator.
1:22:17After dividing you get 0.75.
1:22:20Okay yan
1:22:23multiply by denominator
1:22:25yung four. Ayan sa 3. Tama ba?
1:22:32Teka nga. Balikan natin. Wait lang.
1:22:33Class ha.
1:22:39Okay.
1:22:45Kasi ah yung naging
1:22:48fraction nito is 502. No ito. Hindi siya
1:22:52whole number
1:22:54no. Nung dinivide natin 'tong ah mole.
1:22:57So ang ginamit niyang multiplier
1:23:01o no?
1:23:03Yan. So kaya tayo nag-multiply by 2
1:23:09on each.
1:23:11So ibig sabihin no you have two, you
1:23:15have three.
1:23:17Okay? So ito yung kanyang empirical
1:23:19formula no.
1:23:22Ayan.
1:23:26Ah okay. Kung ano kung 5 kasi 1/2 T's
1:23:30yung denominator non is 2.
1:23:34Kung
1:23:3566 naman 2/3 yung denominator niya ay 3.
1:23:3975 is 3/4 denominator niya is 4. No?
1:23:43Ayun. So doon nakuha yung numbers na yun
1:23:45na pinang-multiply.
1:23:49Okay. Ayun.
1:23:56Hala, nag-move ng ano. Ayan.
1:24:01Calculating molecular formula from
1:24:03empirical formula. No? Ayan. So if
1:24:09a molar mass is known,
1:24:13the molecular formula can be calculated
1:24:15from empirical formula.
1:24:19Yan. So ito yung um
1:24:23working equation. Sige tingnan nga
1:24:25natin.
1:24:38Okay. Some empirical and molecular
1:24:41formulas.
1:24:44Ayan.
1:24:48Okay. Solving for n.
1:24:51Okay. Molecular formula can be
1:24:53calculated from empirical formula if
1:24:55compounds of molar mass is known. Noan.
1:25:00So molecular formula is equals to
1:25:04multiple of empirical formula. Ayan. So
1:25:07yung mu-multiply lang daw. Determining
1:25:09the number of n gives the molecular
1:25:12formula. No?
1:25:15So molar mass over mass over empirical
1:25:17formula is equals to the number of n
1:25:20number of empirical units.
1:25:24Okay.
1:25:26So sige nga try natin 'to. Ayan. So dito
1:25:32okay so yung molar mass daw nito no
1:25:36is 32.5 5
1:25:39grams.
1:25:42Now, uh what is the molecular formula?
1:25:47No,
1:25:49hindi a compound pala no. A compound
1:25:52with an empirical formula. Teka wait
1:25:54lang class.
1:25:58Was found to have a molar mass of 32.05
1:26:03gr.
1:26:05Okay.
1:26:07Ayan. So ang uh
1:26:11mass
1:26:13okay nung empirical uh formula natin. So
1:26:16we have
1:26:18teka nga wait lang class. Magpapalit ako
1:26:21ng ano ayan
1:26:24NH2
1:26:26for every nitrogen you have 14
1:26:31hydrogen. You have 1
1:26:34na lang. Ayan, simplify natin.
1:26:38So, all in all, no, you should have 16.
1:26:42Yan.
1:26:48Mhm. Ayan.
1:26:54Okay.
1:26:59Okay. Tapos ah itong 16 no, we use this.
1:27:03So yung 32 divided by 16 no? 16 yung
1:27:07value nito.
1:27:10Teka.
1:27:13Ay nagla-log.
1:27:22Yan 16 yung value nito.
1:27:25Okay. So 32/ 16 you should have 2 no?
1:27:30Okay? Ito yung magiging value nung n.
1:27:33Okay. Now
1:27:36ang sabi no molecular yung molecular
1:27:39formula is equal sa empirical formula.
1:27:42So EF.
1:27:44So ito yung E.
1:27:48Teka.
1:27:51Ayan. F.
1:28:01Yan.
1:28:09Ito yung EF empirical formula.
1:28:12Ayan. kita.
1:28:15Tapos yung N, ito yung na-calculate
1:28:17natin.
1:28:21Ayan. So,
1:28:24okay. Ito yung empirical formula
1:28:27value ng N. So pagka
1:28:30minultiply mo, you would get the
1:28:31molecular
1:28:33formula. No,
1:28:41ayan. class. Okay. Class. May questions
1:28:45ba? So far may clarification kayo
1:28:48nasundan.
1:28:50Ah medyo mahaba 'tong chapter 7 ano?
1:28:53Ayan.
1:28:58Okay. Sige. O ito ang empirical formula
1:29:03natin is NO2. Okay. Was found to have a
1:29:06molar mass of 92. Yan. So ano ba ang
1:29:12molar mass nung empirical formula? I
1:29:14mean ano ba yung uh weight na pinapakita
1:29:18doon sa empirical formula? So you have
1:29:21isang nitrogen, dalawang oxygen. So
1:29:23basically no you have 14 + 32 so you
1:29:28should have 40
1:29:316.
1:29:33Okay? Tapos china-chat ko na lang class
1:29:36ha. 92 / 46 you should have no ah 2
1:29:43yan. So ibig sabihin yung NO2 would have
1:29:48to be multiplied by 2.
1:29:51So the final answer should be ano ba?
1:29:56What's your final answer? Ayan B.
1:30:00No yung tamang sagot. Ayan na po.
1:30:04Ayan. Okay.
1:30:11Teka nga. Wait lang. Classing natin kung
1:30:12ilan pa 'to.
1:30:15Malapit na. Ilang slides na lang. Kaya
1:30:18na yan. Seven slides na lang. CL
1:30:21baka last na to.
1:30:23calculating the molecular formula for
1:30:26propyine.
1:30:30Okay. So
1:30:33ayan
1:30:35at 14.3%
1:30:38hydrogen, 85.7%
1:30:40carbon and has a molar mass of 42.08
1:30:45gr. What is the molecular formula, no?
1:30:49Ayan. So how would you do this no? Ayan
1:30:53tingnan natin.
1:30:56Okay. So first no
1:31:01kinonvert muna. Ay I mean okay plan
1:31:04calculate the empirical formula then
1:31:06determine the molecular formula. Okay.
1:31:09Step one find element masses.
1:31:13Okay. So binigay kasi yung percentage
1:31:15nila.
1:31:17So based on 100 grams
1:31:20no ito yung kanilang timbang.
1:31:23Okay then ah
1:31:27okay their moles were obtained kinuha.
1:31:30Ayan ito yung moles nila.
1:31:40Okay.
1:31:45Okay. And then um
1:31:49ayan
1:31:52ah ito na yung ano ah magsasabi kung ano
1:31:54yung kanilang empirical formula. So
1:31:57empirical formula is CH2.
1:31:59Yan. Now na siya. 'Di ba?
1:32:04Ah, we need the value of n na 'yung
1:32:07multiplier for the empirical formula to
1:32:09know the exact molecular formula. So ang
1:32:13ginawa natin,
1:32:17okay, ah ito yung experimental.
1:32:22Ito naman yung ano ah mass based on the
1:32:27empirical formula. Ayan.
1:32:30So ang nangyari no ah we have three. So
1:32:33ibig sabihin
1:32:36yung uh compound natin yung molecular
1:32:39formula natin should have
1:32:42C3
1:32:44H6
1:32:45no?
1:32:47Ayan. So dapat C3H6 siya.
1:32:52Ayan. So ayun yun na no.
1:32:55Yan. So ito yung molecular formula niya.
1:32:57C3H6.
1:33:03Okay.
1:33:05For this one naman. Ayan. So ganun din
1:33:07yung procedure no. Ah we're given
1:33:11percentage.
1:33:12Okay. So iwa-100 niyo siya no? So 80 gr
1:33:17for carbon, 20 gr for hydrogen.
1:33:20Okay? Then convert 2 moles.
1:33:25And then you would get the empirical
1:33:27formula. Empirical formula mass divided
1:33:31by with the experimental.
1:33:34Ito ano t's makukuha niya yung value ng
1:33:37nung multiplier for the empirical
1:33:40formula no yan. So ganun din same
1:33:43procedure.
1:33:45Ayan
1:33:50okay empirical formula.
1:33:53Okay two. So dapat ang sagot natin is
1:33:57teka ang naging empirical formula kasi
1:33:59CH3. So dapat ang sagot natin is C2H6.
1:34:05Ayan.
1:34:08Ayun na no. CL uh that's the end of this
1:34:13uh chapter
1:34:17no. Um okay ganito ah.
1:34:22In your LMS, mag-iiwan ako ano anong
1:34:24oras na ba? Mag-iiwan ako ng practice uh
1:34:28questions. Okay lang ba sa inyo?
1:34:35Mm.
1:34:38Ayun.
1:34:49Okay.
1:35:01Ayan.
1:35:05Okay. Sige. Ah, mag-iiwan ako ng ano ng
1:35:09sample problem ha.
1:35:12May questions po ba?

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