RPAL Mole Ratios

Question 1

What is a mole ratio in a chemical reaction?

Accepted Answer

The ratio of moles of one substance to moles of another, derived from the balanced equation

Answer

The ratio of masses of reactants to products

Answer

The number of moles of product per liter of solution

Answer

The ratio of molar masses of reactants

Question 2

In the balanced equation 2H₂ + O₂ → 2H₂O, what is the mole ratio of H₂ to H₂O?

Accepted Answer

2:2 (or 1:1)

Answer

2:1

Answer

1:2

Answer

1:1 only if masses are equal

Question 3

For N₂ + 3H₂ → 2NH₃, what is the mole ratio of H₂ to NH₃?

Accepted Answer

3:2

Answer

1:2

Answer

2:3

Answer

3:1

Question 4

Why must an equation be balanced before using mole ratios?

Accepted Answer

Because mole ratios are derived from stoichiometric coefficients, which are only correct in a balanced equation

Answer

Because unbalanced equations have no products

Answer

Because balancing changes the identity of the substances

Answer

Because mole ratios only apply to gases

Question 5

Using the mole ratio, if you have 4 mol H₂ reacting via 2H₂ + O₂ → 2H₂O, how many moles of O₂ are needed?

Accepted Answer

2 mol O₂

Answer

4 mol O₂

Answer

1 mol O₂

Answer

8 mol O₂

Question 6

For 4Fe + 3O₂ → 2Fe₂O₃, what is the mole ratio of Fe to Fe₂O₃?

Accepted Answer

4:2 (or 2:1)

Answer

1:1

Answer

3:2

Answer

4:3