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Worksheets

Math in chemistry

Total questions: 15

Worksheet time: 15mins

Name
Class
Date
1.

Which formula is the empirical formula for ethane, C₂H₆?

a)

CH₃

b)

C₄H₁₂

c)

C₂H₆

d)

CH

2.

Given a balanced equation representing a reaction: 2CO(g) + O₂(g) → 2CO₂(g) + energy. Which mass of O₂(g) reacts completely with 5.6 grams of CO(g) to produce 8.8 grams of CO₂(g)?

a)

14.4 g

b)

1.6 g

c)

2.8 g

d)

3.2 g

3.

Given the balanced equation representing a reaction: 2KClO₃ → energy → 2KCl + 3O₂. What is the mass of KCl produced when 24.51 grams of KClO₃ reacts completely to produce 9.60 grams of O₂?

a)

43.71 g

b)

34.11 g

c)

14.91 g

d)

5.31 g

4.

What is the gram-formula mass of Mg(NO₃)₂?

a)

172 g/mol

b)

134 g/mol

c)

86 g/mol

d)

148 g/mol

5.

Given the balanced equation for the reaction of butane and oxygen: 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O + energy. How many moles of carbon dioxide are produced when 5.0 moles of butane react completely?

a)

20. mol

b)

10. mol

c)

5.0 mol

d)

40. mol

6.

Given the balanced equation representing the reaction between methane and oxygen: CH₄ + 2O₂ → CO₂ + 2H₂O. According to this equation, what is the mole ratio of oxygen to methane?

a)

2 grams O₂ / 1 gram CH₄

b)

1 gram O₂ / 2 grams CH₄

c)

2 moles O₂ / 1 mole CH₄

d)

1 mole O₂ / 2 moles CH₄

7.

One mole of bromine gas, Br₂, has a mass of

a)

79.9 g

b)

35.0 g

c)

70.0 g

d)

159.8 g

8.

A solution contains 25 grams of KNO₃ dissolved in 200. grams of H₂O. Which numerical setup can be used to calculate the percent by mass of KNO₃ in this solution?

a)

25g / 175g × 100

b)

200g / 225g × 100

c)

25g / 200g × 100

d)

25g / 225g × 100

9.

What is the number of moles in a 78.8-gram sample of MgCO₃ (gram-formula mass = 84.3 g/mol)?

a)

0.935 mol

b)

1.070 mol

c)

0.843 mol

d)

0.949 mol

10.

Which numerical setup can be used to calculate the formula mass of C₉H₁₁NO₂?

a)

12 u + 1 u + 14 u + 16 u

b)

9(6 u) + 11(1 u) + 1(7 u) + 2(8 u)

c)

9 u + 11 u + 1 u + 2 u

d)

9(12 u) + 11(1 u) + 1(14 u) + 2(16 u)

11.

What is the mass of 1.5 moles of CO₂?

a)

66 g

b)

44 g

c)

33 g

d)

29 g

12.

A 2.5 L sample of SO₂(g) at STP and a 2.5 L sample of CO₂(g) at STP can be differentiated by comparing their

a)

phases

b)

temperatures

c)

masses

d)

volumes

13.

Which term represents the sum of the atomic masses of the atoms in a molecule?

a)

percent composition by mass

b)

mass number

c)

formula mass

d)

atomic number

14.

Which compound has the greatest percent composition by mass of sulfur?

a)

MgS

b)

SrS

c)

BaS

d)

CaS

15.

Which two terms represent types of chemical formulas?

a)

empirical and molecular

b)

polar and nonpolar

c)

synthesis and decomposition

d)

saturated and concentrated