WHE #2

Mole Problems

100

How many moles are in 25 g of H₂O?

1.39 mol

200

Oxygen atoms in 4.90 mol in Al₂O₃

8.85 x 10²⁴

300

Hydrogen Atoms in 3.14 mol of H₂O

3.78 x 10²⁴ atoms

400

Nitrogen atoms in 2.79 mol of NH₃

1.68 x 10²⁴ atoms

500

How many atoms are in a 3.56 g sample of Cu? 

3.37 x 10²²

Empirical Formula

100

88.8% copper; 11.2% oxygen

Cu₂O

200

5.88% hydrogen; 94.12% oxygen

HO

300

70.0% iron; 30.0% oxygen

4. Fe₂O₃

400

7.19% phosphorus; 92.81% bromine

PBr₅

500

40% carbon; 6.7% hydrogen; 53.3% oxygen

CH₂O

Molecular Formulas

100

A compound with an empirical formula of C₂OH₄ and a molar mass of 88 grams per mole. What is the molecular formula of this compound?

C₄O₂H₈

200

A compound with an empirical formula of C₂H₈N and a molar mass of 46 grams per mole. What is the molecular formula of this compound?

C₂H₈N

300

The empirical formula is C₅H₄ and its molar mass is 128.16g/mol. Find the molecular formula.

C₁₀H₈

400

A compound with the following composition has a molar mass of 60.10g/mol: 39.97% carbon; 13.41% hydrogen; 46.62% nitrogen. Find the molecular formula.

C₂H₈N₂

500

A compound with an empirical formula of CFBrO and a molar mass of 254.7 grams per mole. What is the molecular formula of this compound?

C₂F₂Br₂O₂

Percent Composition

100

CuBr₂

Cu: 28.4% Br: 71.6%

200

N₂S₂

N: 30.4% S: 69.6%

300

HCl

H:  3% Cl: 97%

400

Mg(NO₃)₂

Mg:  16% N: 19% O: 65%

500

(NH₄)₂S

N: 41.1% H: 11.8% S: 47.1%

Molar Mass

100

What is the molar mass of AlSO₃

107 mol

200

What is the molar mass of HeNO₃? 

66 mol

300

What is the Molar mass of CClO

63.45 mol

400

What is the molar mass of NaHCO₃ ?

83.98 mol

500

What is the molar mass of AgClO₃ ?

191.31 mol