Chem 111 7.1 Notes Mole-Mole- SI unit for amount of matter SI unit for amount of matter

molmol 6.02 X 106.02 X 102323 representative particles= representative particles=

Avogadro’s NumberAvogadro’s NumberYou have to know which type of particle You have to know which type of particle

to pickto pick•Atom (Fe, C)Atom (Fe, C)

•Molecule (molecular compounds; CHMolecule (molecular compounds; CH44))

•Formula Units (salts, ionic compounds; Formula Units (salts, ionic compounds; NaCl)NaCl)

•Ions (Na+)Ions (Na+)

Be able to convert from moles to Be able to convert from moles to particles:particles: Multiply by:Multiply by:

6.02 X 106.02 X 102323 particles particles

1mol1mol

How many molecules are in How many molecules are in 0.360 mol of water?0.360 mol of water?

Be able to convert from particles to Be able to convert from particles to moles:moles: Multiply by:Multiply by:

1 mol 1 mol

6.02 X 106.02 X 102323 particles particles

How many moles of Mg are in How many moles of Mg are in 1.25 X101.25 X102323 atoms? atoms?

Can also find the number of atoms in molCan also find the number of atoms in mol 1. Convert moles to particles1. Convert moles to particles

6.02 X 106.02 X 102323 particles particles

1mol1mol

2. Convert molecules to atoms:2. Convert molecules to atoms:

# atoms# atoms

1 molecule (particle)1 molecule (particle)

How many atoms are in 2.12 mol of How many atoms are in 2.12 mol of CC33HH88??

Ex. How many moles are in 4.65 X Ex. How many moles are in 4.65 X 10102424 molecules of NO molecules of NO22??

Molar MassMolar Mass- mass of 1 mol in g, - mass of 1 mol in g, use periodic table & add up the masses,use periodic table & add up the masses, round to 2 spaces past the decimalround to 2 spaces past the decimal

Types of molar mass:Types of molar mass: Gram atomic massGram atomic mass-- (gam) atomic (gam) atomic

mass of an element expressed in g mass of an element expressed in g Gram molecular massGram molecular mass-- (gmm) (gmm)

molecular mass of a molecule molecular mass of a molecule expressed in gexpressed in g

Gram formula massGram formula mass-- (gfm) formula (gfm) formula mass of a salt expressed in gmass of a salt expressed in g

Find the molar mass & number Find the molar mass & number of particles of the following: of particles of the following:

1 mol C1 mol C 1 mol CH1 mol CH44

1 mol (NH1 mol (NH44))22COCO33

1 mol CaCl1 mol CaCl22

7.2 Notes Be able to convert moles to mass:Be able to convert moles to mass:

Multiply by: Multiply by: Molar mass (g)Molar mass (g)

1 mol1 mol

How many g are in 9.45 mol How many g are in 9.45 mol NN22OO33??

Be able to convert mass to Be able to convert mass to moles:moles:

Multiply by: Multiply by: 1 mol 1 mol

Molar mass Molar mass (g)(g)

How many moles are in 92.2 g How many moles are in 92.2 g FeFe22OO33??

For all substances:For all substances: 1 mol=molar mass=6.02 X 101 mol=molar mass=6.02 X 1023 23 particlesparticles

FOR GASES ONLY:FOR GASES ONLY: 1 mol=molar mass=6.02 X 101 mol=molar mass=6.02 X 1023 23 particlesparticles AND at AND at STPSTP (standard temperature & (standard temperature &

pressure) OC &101.3kpa or 1 atm 1mol= pressure) OC &101.3kpa or 1 atm 1mol= 22.4L22.4L

Molar volumeMolar volume- 1 mol of gas at STP has - 1 mol of gas at STP has 22.4 L 22.4 L

Convert molConvert mol volume volume Multiply by:Multiply by:

22.4L22.4L1 mol1 mol

Determine the volume of 0.60 mol SODetermine the volume of 0.60 mol SO22 at STP.at STP.

To convert from volumeTo convert from volumemol invert the mol invert the conversion factorconversion factor

Determine the number of moles in 2 L Determine the number of moles in 2 L of COof CO22 gas at STP. gas at STP.

Can also use density to solve problemsCan also use density to solve problems

D=mass/volume= m/v=g/LD=mass/volume= m/v=g/L

D of a gas containing C & O is 1.964 g/L at D of a gas containing C & O is 1.964 g/L at STP. Determine that molar mass.STP. Determine that molar mass.

What is the density of krypton gas at STP?What is the density of krypton gas at STP?

Multi-step problems- convert to Multi-step problems- convert to moles then to desired unitmoles then to desired unit

Calculate the number of molecules Calculate the number of molecules in 60.0g NOin 60.0g NO22..

LabLab Title:Title: The Mole The Mole Purpose:Purpose: To find the number of moles To find the number of moles

present in a given samplepresent in a given sample Materials:Materials: sample, balance, weigh boat sample, balance, weigh boat Procedure:Procedure:

1. Put weigh boat on balance & pres 1. Put weigh boat on balance & pres taretare

2. Add sample to weigh boat & record 2. Add sample to weigh boat & record massmass

3. Return sample to vial3. Return sample to vial Observations:Observations:

Mass of sample _________ Mass of sample _________ Name of sample ________Name of sample ________

Conclusion Questions:Conclusion Questions: Copy & Answer, Show ALL Work for Copy & Answer, Show ALL Work for

CreditCredit 1. How many moles did your sample contain?1. How many moles did your sample contain? 2. How much would one mole of your sample 2. How much would one mole of your sample

contain?contain? 3. How many particles would 1 mole of your 3. How many particles would 1 mole of your

sample contain?sample contain? 4. How many grams would 2 moles of your 4. How many grams would 2 moles of your

sample contain?sample contain? 5. How many particles would 2 moles of your 5. How many particles would 2 moles of your

sample contain?sample contain? 6. On a scale of 1(awesome)-5(awful), how 6. On a scale of 1(awesome)-5(awful), how

would you rate your performance on this lab? would you rate your performance on this lab? Explain.Explain.

7. Write a 2 sentence conclusion for this lab. 7. Write a 2 sentence conclusion for this lab.

7.3 Notes % Composition% Composition: relative amount of : relative amount of

each element in compound or % by each element in compound or % by mass of each element in compoundmass of each element in compound

% mass= % mass= g desired elementg desired element X X 100100

total g of compoundtotal g of compound Make sure the % add up to 100.Make sure the % add up to 100.

If 8.20 g Mg combines with 5.40g O, If 8.20 g Mg combines with 5.40g O, what is the % of each compound?what is the % of each compound?

Calculate the % composition of CCalculate the % composition of C33HH88

Can use as conversion factor:Can use as conversion factor:

Mass element in Mass element in formula(molecule)formula(molecule)

Total mass of formula (molecule)Total mass of formula (molecule)

Calculate mass C in 82.0g CCalculate mass C in 82.0g C33HH88

Empirical FormulaEmpirical Formula- lowest whole - lowest whole number ratio of elements in a compoundnumber ratio of elements in a compound

Molecular formulaMolecular formula- # of elements in a - # of elements in a compound as it appears in naturecompound as it appears in nature May or may not be the same as May or may not be the same as

empiricalempirical

HO is empirical formulaHO is empirical formula HH22OO22 is molecular is molecular

COCO22 empirical & molecular are the same empirical & molecular are the same

To find empirical formula:To find empirical formula: 1. Change % to g1. Change % to g 2. Change g to mol2. Change g to mol 3. Find ratio of moles3. Find ratio of moles 4. Ratios become subscripts in 4. Ratios become subscripts in

formulaformula Tricks- if molar ratio is:Tricks- if molar ratio is:

– .5 X by 2.5 X by 2– .3 or .6 X 3.3 or .6 X 3– .25 or .75 X 4.25 or .75 X 4– .2 or lower, round down.2 or lower, round down– .8 or above round up.8 or above round up

Determine the empirical formula of Determine the empirical formula of a compound that a compound that contains35.98%Al & 64.02%S.contains35.98%Al & 64.02%S.

What is the empirical formula of a What is the empirical formula of a compound that is 25.9 % N & compound that is 25.9 % N & 74.1%O?74.1%O?

What is the empirical formula of a What is the empirical formula of a compound that contains compound that contains 10.89%Mg, 31.77%Cl & 57.34%O?10.89%Mg, 31.77%Cl & 57.34%O?

If they give you molecular mass:If they give you molecular mass: 1. Get mass of empirical formula 1. Get mass of empirical formula

(what you just found)(what you just found) 2. Divide molecular mass/empirical2. Divide molecular mass/empirical 3. Multiply that # by subscripts3. Multiply that # by subscripts

Calculate molecular formula of Calculate molecular formula of compound whose molar mass is compound whose molar mass is 60.0g & the empirical formula is 60.0g & the empirical formula is CHCH44N.N.

A compound is composed of A compound is composed of 40.68% C, 5.08% H & 54.24%O. It 40.68% C, 5.08% H & 54.24%O. It has a molecular mass of has a molecular mass of 118.1g/mol. Find the empirical & 118.1g/mol. Find the empirical & molecular formula.molecular formula.

Lab: Lab: Title:Title: % Composition of Gum % Composition of Gum Purpose:Purpose: To find the % of sugar in gum To find the % of sugar in gum Materials:Materials: Watch, gum, balance Watch, gum, balance Procedure:Procedure:

1. Get balance from cabinet1. Get balance from cabinet 2. Mass gum IN WRAPPER2. Mass gum IN WRAPPER 3. Take gum out of wrapper & chew for 15 3. Take gum out of wrapper & chew for 15

minutesminutes 4. While chewing gum, mass wrapper4. While chewing gum, mass wrapper 5. After 15 min, put gum 5. After 15 min, put gum backback in wrapper in wrapper

& get mass& get mass

Observations:Observations: Mass of gum in wrapper _______Mass of gum in wrapper _______ Mass of wrapper __________Mass of wrapper __________ Mass of gum after chewing _______Mass of gum after chewing _______

Calculations:Calculations: 1. Find true mass of gum by subtracting 1. Find true mass of gum by subtracting

the mass of the wrapper from the the mass of the wrapper from the chewed & unchewed gum ___________chewed & unchewed gum ___________

2. Subtract unchewed mass from chewed 2. Subtract unchewed mass from chewed mass (this is the mass of the sugar)mass (this is the mass of the sugar)

Find the % sugar in the gumFind the % sugar in the gum Conclusions:Conclusions: Write a sentence Write a sentence

summing up your datasumming up your data