The Mole To play the movies and simulations included, view the presentation in Slide Show Mode. 6.02 X 1023.

The Mole To play the movies and simulations included, view the presentation in Slide Show Mode. 6.02 X 1023

The Mole A counting unit
Similar to a dozen, except instead of 12, it’s 602 billion trillion 602,000,000,000,000,000,000,000 6.02 X 1023 (in scientific notation) This number is named in honor of Amedeo _________ (1776 – 1856)

The word “mole” was introduced about 1896 by Wilhelm Oswald, who derived the term from the latin word moles meaning a “heap” or “pile.” The mole, whose abbreviation is “mol”, is the SI base unit for measuring amount of a pure substance.

The Mole 1 dozen cookies = 12 cookies
1 mole of cookies = 6.02 X 1023 cookies 1 dozen cars = 12 cars 1 mole of cars = 6.02 X 1023 cars 1 dozen Al atoms = 12 Al atoms 1 mole of Al atoms = 6.02 X 1023 atoms Note that the NUMBER is always the same, but the MASS is very different! Mole is abbreviated mol (gee, that’s a lot quicker to write, huh?)

A Mole of Particles Contains 6.02 x 1023 particles
= x 1023 C atoms = x 1023 H2O molecules = x 1023 NaCl “molecules” (technically, ionics are compounds not molecules so they are called formula units) 6.02 x 1023 Na+ ions and 6.02 x 1023 Cl– ions 1 mole C 1 mole H2O 1 mole NaCl

Important Words Atom: the smallest indivisible unit of an element.
Molecule: a group of atoms chemically bonded together. Diatomic molecule: these elements exists as a 2-atom molecule e.g. H2, N2, O2, F2, Cl2, Br2, I2 Particle: any small bit of matter, including ions, atoms and molecules. To play the movies and simulations included, view the presentation in Slide Show Mode.

REPRESENTATIVE PARTICLES & MOLES
ATOMIC NITROGEN ATOM N 6.02x1023 NITROGEN GAS MOLEC. N2 WATER H20 CALCIUM ION ION Ca2+ CALCIUM FLUORIDE FORMULA UNIT CaF2 CHEMICAL REP. PARTICLE SUBTANCE REPRESENTATIVE PARTICLE FORMULA IN 1 MOL

Avogadro’s Number as Conversion Factor
6.02 x 1023 particles 1 mole or 1 mole Note that a particle could be an atom OR a molecule!

How we measure moles…

Learning Check 1. Number of atoms in 0.500 mole of Al a) 500 Al atoms
b) x 1023 Al atoms c) x 1023 Al atoms 2.Number of moles of S in 1.8 x 1024 S atoms a) mole S atoms b) mole S atoms c) x 1048 mole S atoms

How we measure moles…

How we measure moles… Do you know how to measure out 3 moles of sugar or salt or water? The mole is a counting unit, so we would have to count out 6.02x1023 particles of each substance. (no thank you) There are 2 ways we can use to measure out a number of moles of a substance. Measure it in grams (a mass) Or measure it in liters (a volume)

Molar Mass The Mass of 1 mole (in grams)
Equal to the numerical value of the average atomic mass (get from periodic table) 1 mole of C atoms = g 1 mole of Mg atoms = 24.3 g 1 mole of Cu atoms = 63.5 g

Learning Check! = 79.9 g/mole 1 mole of Br atoms 1 mole of Sn atoms
Find the molar mass (usually we round to the tenths place) = 79.9 g/mole 1 mole of Br atoms 1 mole of Sn atoms = g/mole

Molar Mass mass of ONE MOLE of particles. On the periodic table, the atomic mass (a.m.u.) is the same as the molar mass (g/mol), which means the mass for one mole or for 6.02 x 1023 atoms of the element. To play the movies and simulations included, view the presentation in Slide Show Mode.

Relative Mass It is very difficult to determine the mass of a single atom precisely and accurately, so scientists determine the mass of elements by comparing their “RELATIVE MASS”, which is a mass ratio between two elements. To play the movies and simulations included, view the presentation in Slide Show Mode.

Examples & Equivalences:
1 mole of C = __________ atoms of C = _______a.m.u. (atomic mass unit) = ___________ g/mole 1 mole of O = __________ atoms of O = _______a.m.u. (atomic mass unit) = ___________g/mole 1 mole of O2 = _________ molecules of O2 = _______a.m.u. (atomic mass unit) = ________g/mole To play the movies and simulations included, view the presentation in Slide Show Mode.

Molar Mass of Compound Look up the molar mass of each element from a periodic table. Determine the number of atoms for each element (shown by the subscript). Multiply the molar mass of each element by the number of atoms of that element in the compound. Add up the numbers produced in step 3. Express the molar mass in proper unit: g/mol * Round the molar masses to one decimal place for precision and accuracy reason. * Don’t worry about significant figures here! To play the movies and simulations included, view the presentation in Slide Show Mode.

Molar Mass of Molecules and Compounds
Mass in grams of 1 mole equal numerically to the sum of the atomic masses 1 mole of CaCl2 = g/mol 1 mole Ca x 40.1 g/mol + 2 moles Cl x 35.5 g/mol = g/mol CaCl2 1 mole of N2O4 = 92.0 g/mol

Learning Check To play the movies and simulations included, view the presentation in Slide Show Mode.

Calculate the molar mass of Cu(NO3)2  6H2O
Molar Mass of Compound Example 3: Calculate the molar mass of Cu(NO3)2  6H2O To play the movies and simulations included, view the presentation in Slide Show Mode.

Learning Check! Molar Mass of K2O = ? Grams/mole
B. Molar Mass of antacid Al(OH)3 = ? Grams/mole

Calculations with Molar Mass
Grams Moles

Representative Particles 1 mole 6.02x10 23 Mole 1 mole 6.02x10 23 atomic 1 mole mass atomic mass 1 mole Mass

Converting Moles and Grams
Aluminum is often used for the structure of light-weight bicycle frames. How many grams of Al are in 3.00 moles of Al? 3.00 moles Al ? g Al

1 mol C3H8O molecules = 8 mol H atoms
How many H atoms are in 72.5 g of C3H8O ? 1 mol C3H8O = (3 x 12) + (8 x 1) + 16 = 60 g C3H8O 1 mol C3H8O molecules = 8 mol H atoms 1 mol H = x 1023 atoms H 5.82 x 1024 atoms H Let’s do some more…………..

Avogadro Hypothesis equal volumes of gases at the same temperature and pressure contain the same number of molecules regardless of their chemical nature and physical properties. To play the movies and simulations included, view the presentation in Slide Show Mode.

Calculations with Molar Volume
1 mole of any gas at STP has volume 22.4L STP: STANDARD TEMPERATURE AND PRESSURE = 0C and KPa molar volume Volume Moles

Representative Particles Volume of Gas at STP atomic 1 mole mass Mass 22.4 L Representative Particles Volume of Gas at STP 6.02x10 23 Mole 1 mole 1 mole 22.4 L 6.02x10 23 Mole 1 mole 6.02x10 23 1 mole 22.4 L atomic 1 mole mass atomic mass 1 mole Mass

1. Molar mass of Al 1 mole Al = 27.0 g Al
2. Conversion factors for Al 27.0g Al or mol Al 1 mol Al g Al 3. Setup 3.00 moles Al x g Al 1 mole Al Answer = g Al

Learning Check! The artificial sweetener aspartame (Nutra-Sweet) formula C14H18N2O5 is used to sweeten diet foods, coffee and soft drinks. How many moles of aspartame are present in 225 g of aspartame?

The molar volume of any gas a STP standard temperature (0 0C) and pressure (101kPa) is 22.4 L.
Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP.

Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs

Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs x kg 2.21 lbs

Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs x kg x g 2.21 lbs kg

Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs x kg x g x 1 mole 2.21 lbs kg g

Molar Volume is 22.4 L 1 mole memorize! Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs x kg x g x 1 mole x L 2.21 lbs kg g mole

Molar Volume is 22.4 L 1 mole memorize! 1. Calculate the volume of 10.0 lbs of CO2 at STP. 10.0 lbs x kg x g x 1 mole x L = x 103 L 2.21 lbs kg g mole

3. 10. 62 g of a common gas occupies 8. 50 L at STP. Calculate
g of a common gas occupies 8.50 L at STP. Calculate the molar mass of the gas and determine the gas. 8.50 L x 1 mole = moles 22.4 L Molar Mass = grams moles = g = 28.0 g/mole moles The gas is N2

Everything must go through Moles!!!
Calculations molar mass Avogadro’s number Grams Moles particles Everything must go through Moles!!!

Atoms/Molecules and Grams
How many atoms of Cu are present in 35.4 g of Cu? 35.4 g Cu mol Cu X 1023 atoms Cu g Cu mol Cu = 3.4 X 1023 atoms Cu

Learning Check! How many atoms of K are present in 78.4 g of K?

Learning Check! What is the mass (in grams) of 1.20 X 1024 molecules of glucose (C6H12O6)?

Learning Check! How many atoms of O are present in 78.1 g of oxygen?
78.1 g O2 1 mol O X 1023 molecules O2 2 atoms O g O mol O molecule O2

Representative Particles Volume of Gas at STP atomic 1 mole mass Mass 22.4 L Representative Particles Volume of Gas at STP 6.02x10 23 Mole 1 mole 1 mole 22.4 L 6.02x10 23 Mole 1 mole 6.02x10 23 1 mole 22.4 L Density atomic 1 mole mass atomic mass 1 mole Mass

Calculating Density Find density of Oxygen at STP?
Find density of Carbon dioxide at STP? Find density of Nitrogen at STP? Find density of Hydrogen at STP?

Calculating Molar Mass
1.35 L of diborane gas has a mass of 1.67 g at STP, Find molar mass Unit of molar mass= g mol

Calculating Molar Volume
What is the molar volume of quartz, SIO2? Density is 2.64 g/mL molar volume = L 1 mol Unit of molar volume = L mol

Percent Composition Can be determined by analysis
Or, if you know the formula just assume you have 1 mole Divide the mass of each element by the formula mass of the compound

Percent Composition of H2O
2 X H = 2 X 1.0 g = 2.0 g 1 X O = 1 X 16.0 g = 16.0 g Molar mass = 2.0 g g = 18.0 g % H = 2.0g X 100% = 11.2% 18.0g % O = 16.0g X 100% = 88.8%

Atomic Mass of elements
The atoms of each element have a different mass. Carbon is given a relative atomic mass (RAM) of 12. The RAM of other atoms compares them with carbon. Eg. Hydrogen has a mass of only one twelfth that of carbon and so has a RAM of 1. Below are the RAMs of some other elements. Element Symbol Times as heavy as carbon R.A.M Helium He one third Beryllium Be three quarters Molybdenum Mo Eight Krypton Kr Seven Oxygen O One and one third Silver Ag Nine Calcium Ca Three and one third 4 9 96 84 16 108 40

Formula Mass For a number of reasons it is useful to use something called the formula mass. To calculate this we simply add together the atomic masses of all the atoms shown in the formula. (N=14; H=1; Na=23; O=16; Mg=24; Ca=40) Substance Formula Formula Mass Ammonia NH3 Sodium oxide Na2O Magnesium hydroxide Mg(OH)2 Calcium nitrate Ca(NO3)2 14 + (3x1)=17 (2x23) + 16 =62 24+ 2(16+1)=58 40+ 2(14+(3x16))=164

Percentage Composition
It is sometimes useful to know how much of a compound is made up of some particular element. This is called the percentage composition by mass. % Z = (Number of atoms of Z) x (atomic Mass of Z) Formula Mass of the compound E.g. % of oxygen in carbon dioxide (Atomic Masses: C=12. O=16) Formula = Number oxygen atoms = Atomic Mass of O = Formula Mass CO2 = % oxygen = CO2 2 12 +(2x16)=44 2 x 16 / 44 = 72.7%

Calculate the percentage of oxygen in the compounds shown below
Activity Calculate the percentage of oxygen in the compounds shown below % Z = (Number of atoms of Z) x (atomic Mass of Z) Formula Mass of the compound Formula Atoms of O Mass of O Formula Mass %age Oxygen MgO 1 K2O NaOH SO2 2 16 24+16=40 16x100/40=40% 16 (2x39)+16 =94 16x100/94=17% =40 16 16x100/40=40% 32 32+(2x16)=64 32x100/64=50%

Activity Nitrogen is a vital ingredient of fertiliser that is needed for healthy leaf growth. But which of the two fertilisers ammonium nitrate or urea contains most nitrogen? To answer this we need to calculate what percentage of nitrogen is in each compound

Formulae: Ammonium Nitrate NH4NO3: Urea CON2H4
Activity Formulae: Ammonium Nitrate NH4NO3: Urea CON2H4 Formula Atoms of N Mass of N Formula Mass %age Nitrogen NH4NO3 2 28 CON2H4 14+(1x4)+14+(3x16)=80 28x100 /80 = 35% 12+16+(2x14+(4x1)= 60 28x100 /60 = 46.7% Atomic masses H=1: C=12: N=14: O=16 And so, in terms of % nitrogen urea is a better fertiliser than ammonium nitrate

Formula from Composition by mass.

Formula Mass When a new compound is discovered we have to deduce its formula. This always involves getting data about the masses of elements that are combined together. What we have to do is work back from this data to calculate the number of atoms of each element and then calculate the ratio. In order to do this we divide the mass of each atom by its atomic mass. The calculation is best done in 5 stages:

We found 3. 2g of copper reacted with 0. 8g of oxygen
We found 3.2g of copper reacted with 0.8g of oxygen. What is the formula of the oxide of copper that was formed? (At. Mass Cu=64: O=16) Substance Copper oxide 1. Elements Cu O 2. Mass of each element (g) 3. Mass / Atomic Mass 4. Ratio 5. Formula 3.2 0.8 3.2/64 =0.05 0.8/16 =0.05 1:1 CuO

We found 5. 5g of manganese reacted with 3. 2g of oxygen
We found 5.5g of manganese reacted with 3.2g of oxygen. What is the formula of the oxide of manganese formed? (Atomic. Mass Mn=55: O=16) Substance Manganese oxide 1. Elements Mn O 2. Mass of each element (g) 3. Mass / Atomic Mass 4. Ratio 5. Formula 5.5 3.2 5.5/55 =0.10 3.2/16 =0.20 1:2 MnO2

Divide biggest by smallest
Activity A chloride of silicon was found to have the following % composition by mass: Silicon 16.5%: Chlorine 83.5% (Atomic. Mass Si=28: Cl=35.5) Substance Silicon Chloride 1. Elements Si Cl 2. Mass of each element (g per 100g) 3. Mass / Atomic Mass 4. Ratio 5. Formula 16.5 83.5 16.5/28 =0.59 83.5/35.5 =2.35 Cl÷Si = (2.35 ÷ 0.59) = (3.98) Ratio of Cl:Si =4:1 Divide biggest by smallest SiCl4

Activity Calculate the formula of the compounds formed when the following masses of elements react completely: (Atomic. Mass Si=28: Cl=35.5) Element 1 Element 2 Atomic Masses Formula Fe = 5.6g Cl=106.5g Fe=56 Cl=35.5 K = 0.78g Br=1.6g K=39: Br=80 P=1.55g Cl=8.8g P=31: Cl=35.5 C=0.6g H=0.2g C=12: H=1 Mg=4.8g O=3.2g Mg=24: O=16 FeCl3 KBr PCl5 CH4 MgO

Percent Composition of C6H12O6
6 X C = 6 X 12g = 72g 12 X H = 12 X 1g = 12g 6 X O = 6 X 16g = 96g Molar mass = grams/mole % C = % H = % O = (72g/180g) X 100% = 40.0% (12g/180g) X 100% = 6.67% (96g/180g) X 100% = 53.3%

Percent composition of an element in a compound
n x molar mass of element molar mass of compound x 100% n is the number of moles of the element in 1 mole of the compound %C = 2 x (12.01 g) 46.07 g x 100% = 52.14% C2H6O %H = 6 x (1.008 g) 46.07 g x 100% = 13.13% %O = 1 x (16.00 g) 46.07 g x 100% = 34.73% 52.14% % % = 100.0% 3.5

Percentage Composition
Remember that you have to calculate the formula mass!

Percent composition of an element in a compound
n x molar mass of element molar mass of compound x 100% n is the number of moles of the element in 1 mole of the compound %C = 2 x (12.01 g) 46.07 g x 100% = 52.14% C2H6O %H = 6 x (1.008 g) 46.07 g x 100% = 13.13% %O = 1 x (16.00 g) 46.07 g x 100% = 34.73% 52.14% % % = 100.0% 3.5

Percent Composition What is the percent carbon in C5H8NO4 (the glutamic acid used to make MSG monosodium glutamate), a compound used to flavor foods and tenderize meats? a) %C b) %C c) %C

Workbook Practice Page 91 Question 44

% Composition of group of atoms
Find % composition of (NH4)2 in (NH4)2C2O4 Page 91 Question 45 f,g ,h

% Composition Lab Lab Groups

My day dream is --------
% Composition Lab Lab Groups My day dream is

Discussion for 5 minutes
% Composition Lab Discussion for 5 minutes 1. What is % composition 2. How to calculate percent composition 2. How to calculate Empirical Formula 3. How to calculate molecular Formula

% Composition Lab Need Mg Electronic Balance Petri Dish small one

Finish Lab and the worksheet Submit the worksheet
% Composition Lab Find % composition of MgO Group of 5 student Have Lab worksheet Finish Lab and the worksheet Submit the worksheet

Types of Formulas Ionic formula are always empirical formula
The formula of a compound that expresses the smallest whole number ratio of the atoms present. Ionic formula are always empirical formula Molecular Formula The formula that states the actual number of each kind of atom found in one molecule of the compound.

Empirical Formula from % compositon
Percent Percent of Elements in the compound Grams Change % to grams Moles Divide by molecular mass Whole Number Ratio Get whole number Ratio Write Formula

A sample of a brown gas, a major air pollutant, is found to contain 2
A sample of a brown gas, a major air pollutant, is found to contain 2.34 g N and 5.34g O. Determine a formula for this substance. require mole ratios so convert grams to moles moles of N = 2.34g of N = moles of N 14.01 g/mole moles of O = g = moles of O 16.00 g/mole Formula:

Empirical Formula from % Composition
A substance has the following composition by mass: % Na ; % B ; % H What is the empirical formula of the substance?

Molecular Formula from Empirical Formula

Calculation of the Molecular Mass
From Density of Gas at STP

From Mass and Volume at STP of Gas at STP

From Moles and mass

From molar mass of some other substance

Finding Molecular Formula
Empirical Mass Empirical Formula % composition of elements , Like 25% C, 75% H Molecular Mass Density (STP) Mole and Mass Multiple of other molecule

Calculation of the Molecular Formula
A compound has an empirical formula of NO2. The colorless liquid, used in rocket engines has a molar mass of 92.0 g/mole. What is the molecular formula of this substance?

Practice Page 95 Q 47-55 Quiz at 13:50

Quiz Question A gas has the percentage composition: 36.84% N and 63.15% O. If the density of the gas is 6.785g/L at STP, what is the molecular formula of the gas?

Answer N4O6

What is the formula mass of MgCl2 ? Mg=24 Cl=35.5
59.5 83.5 95 119

What is the formula mass of Mg(OH)2 ? Mg=24 O=16 H = 1
41 42 57 58

What is the percentage nitrogen in ammonium sulphate (NH4)2SO4?
21% 42% 63% 84%

What is the formula of a compound containing 1. 4g nitrogen and 3
What is the formula of a compound containing 1.4g nitrogen and 3.2g of oxygen? (N=14 O=16) N2O NO NO2 N2O3

What is the formula of a compound containing 6. 5g zinc and 1
What is the formula of a compound containing 6.5g zinc and 1.6g oxygen? (Zn=65 O=16) ZnO Zn2O3 ZnO2 Zn2O

What is the mass of 2 moles of magnesium nitrate Mg(NO3)2?

How many moles of iron atoms is 280g of iron? (Fe=56)
One mole Two moles Four moles Five moles

The Mole To play the movies and simulations included, view the presentation in Slide Show Mode. 6.02 X 1023.

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The Mole To play the movies and simulations included, view the presentation in Slide Show Mode. 6.02 X 1023.

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