03 - Molar Mass - Notes PDF

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3 - Molar Mass

SCH3UE – Stoichiometry

Date: ______________________________________________

Molar Mass No one has yet manufactured a balance that weighs in ____________________ Therefore, a method must be found to convert _____________________________ into a number of ________________________________________ Fortunately, the mass in grams of one mole of atoms is numerically _______________________ to the atomic mass measured in atomic mass units Therefore, the ________________________________________ of molecules is equal to the _____________________________ in atomic mass units Example: Mass of one atom of oxygen ______________________________ Mass of one mole of oxygen ______________________________ Example: Mass of one molecule of carbon dioxide ______________________________

Mass of one mole of carbon dioxide ______________________________

Example: What is the molar mass of NaOH?

Example: What is the molar mass of ammonium phosphate?

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3 - Molar Mass

SCH3UE – Stoichiometry

In Chemistry, all of our calculations are done with ___________________ We need to be able to convert mass to moles We can convert between mass and moles using the following formulae:

Examples: How many grams of NaHCO3 are in 0.673 moles?

How many grams of KMnO4 are in 1.791 moles?

How many moles of CuCl2 are in 126.3 grams?

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3 - Molar Mass

SCH3UE – Stoichiometry

How many moles of Fe2O3 are in 384.0 grams?

How many atoms of gold (Au) are there in 314 grams of gold?

How many atoms are in 83.14 grams of sodium nitrate?

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3 - Molar Mass

SCH3UE – Stoichiometry

Homework 1. Calculate the molar masses of the following chemicals: a) Cl2

b) KOH

c) BeCl2

d) FeCl3

e) BF3

f) CCl2F2

g) Mg(OH)2

h) UF6

i) SO2

j) H3PO4

k) (NH4)2SO4

l) CH3COOH

m) Pb(NO3)2

n) Ga2(SO3)3

o) CuSO4 • 5 H2O

2. Given the following number of grams, find the number of moles: a) 30.6 grams of H3PO4

b) 25.67 grams of HF

c) 110 grams of NaHCO3

d) 1.1 grams of FeCl3

e) 0.987 grams of Ra(OH)2

f) 564 grams of copper

g) 12.3 grams of CO2

h) 89 grams of Pb(CH3COO)4 i) 65.3 grams of NaOH

j) 2.025 grams of CuSO4 • 5 H2O

3. Given the following number of moles, find the mass: a) 4.06 moles of Cu(CN)2

b) 5.60 moles of C6H6

c) 21.3 moles of BaCO3

d) 1.20 moles of (NH4)3PO3 e) 9.3 × 10 moles of SmO f) 6.6 moles of ZnO g) 5.4 moles of K2SO4

h) 88.45 moles of NI3

j) 0.02536 mol of HCl(aq)

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i) 0.541 moles of C8H18

3 - Molar Mass

SCH3UE – Stoichiometry

Answers 1. a) 70.91 g/mol

b) 56.11 g/mol

c) 79.91 g/mol

d) 162.20 g/mol

e) 67.81 g/mol

f) 120.91 g/mol

g) 58.33 g/mol

h) 352.03 g/mol

i) 64.07 g/mol

j) 98.00 g/mol

k) 132.17 g/mol

l) 60.06 g/mol

m) 331.22 g/mol

n) 379.65 g/mol

o) 249.72 g/mol

a) 0.312 mol

b) 1.283 mol

c) 1.3 mol

d) 0.0068 mol

e) 0.00380 mol

f) 8.87 mol

g) 0.279 mol

h) 0.20 mol

i) 1.63 mol

a) 469 g

b) 437 g

c) 4.20 kg

d) 160. G

e) 1.5 g

f) 540 g

g) 940 g

h) 34.91 kg

i) 61.8 g

2.

j) 0.008109 mol

3.

j) 0.9246 g

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