RPAL Mole Ratios 2

Question 1

How is a mole ratio used as a conversion factor?

Accepted Answer

It is placed as a fraction (desired moles / given moles) and multiplied by the known quantity

Answer

A mole ratio serves as a conversion factor: multiply moles of known substance by (moles desired / moles given) from the balanced equation.

Question 2

For 2SO₂ + O₂ → 2SO₃, how many moles of SO₃ are produced from 3 mol SO₂?

Accepted Answer

3 mol SO₃

Answer

The SO₂:SO₃ ratio is 2:2 (1:1), so 3 mol SO₂ produces 3 mol SO₃.

Question 3

For CH₄ + 2O₂ → CO₂ + 2H₂O, how many moles of H₂O are produced from 5 mol CH₄?

Accepted Answer

10 mol H₂O

Answer

The CH₄:H₂O ratio is 1:2, so 5 mol CH₄ produces 5 × 2 = 10 mol H₂O.

Question 4

What is the mole ratio of O₂ to H₂O in the reaction 2H₂ + O₂ → 2H₂O?

Accepted Answer

1:2

Answer

The coefficients give 1 mol O₂ per 2 mol H₂O, so the ratio O₂:H₂O = 1:2.

Question 5

In 2KClO₃ → 2KCl + 3O₂, how many moles of O₂ are produced from 4 mol KClO₃?

Accepted Answer

6 mol O₂

Answer

The KClO₃:O₂ ratio is 2:3, so 4 mol KClO₃ produces 4 × (3/2) = 6 mol O₂.

RPAL - Reactants, Products, and Leftovers Practice Test