Unit 7 Exam

Significant Figures

100

Determine the amount of significant figures : 2.00345

6

200

Determine the amount of significant figures : 0.00602

3

300

Determine the amount of significant figures : 3,000,500

5

400

Determine the amount of significant figures : 20

1

Percent Composition

100

Determine the percent composition of each element in the compound : HCl

H = 2.77%

Cl=97.23%

200

Determine the percent composition of each element in the compound : CF₄

C = 13.65%

F = 86.35%

300

Determine the percent composition of each element in the compound : (NH₄)₂CO₃

N = 29.15%

H = 8.41%

C = 12.50%

O =49.94%

400

Determine the percent composition of each element in the compound : Al₂(SO₄)₃

Al = 15.77%

S = 28.11%

O =56.12%

Percent Error

100

Experimental : 1.544

Actual :2.10

-27% Error

200

Experimental : 103.782

Actual : 105.51

-1.64% Error

300

Experimental : 10.88

Actual : 15.678

-30.6%

400

Experimental : 12.7

Actual : 12.605

0.8% Error

Empirical Formula

100

A compound contains 89.87% calcium and 10.13% carbon

Ca₈C3

200

A compound contains 12.8% carbon, 2.1% hydrogen, and 85.1% Bromine.

CH₂Br

300

A compound contains 24.46 grams oxygen and 1.54 grams hydrogen

OH

400

A compound contains 47.04 grams carbon, 7.84 grams hydrogen, 25.12 grams oxygen

C₅H₁₀O₂

Molecular Formula

100

Empirical Formula : C₃H₄

Molecular Mass : 120.195 g/mol

Molecular Formula : ?

C₉H₁₂

200

Empirical Formula : NaCl

Molecular Mass : 116.88 g/mol

Molecular Formula : ?

Na₂Cl₂

300

Empirical Formula : H₃O

Molecular Mass : 171.207 g/mol

Molecular Formula : ?

H₂₇O₉

400

Empirical Formula : ?

Empirical Mass : 64.04 g/mol 

Molecular Formula : C₃H₁₂O₉

CH₄O₃