Chemical equations and Stoichiometry

2H₂  +   O₂  →  2H₂O
How many moles of oxygen are consumed if 8 moles H₂ are used?

• 2
• 4
• 6
• 8

For the Balanced Reaction: 3 Mg + 1 Fe₂O₃ → 3 MgO + 2 Fe; What is the Ratio of moles of MgO to moles Fe?

• 3mol Mg / 2 mol Fe
• 2 mol Mg/ 3 mol Fe
• 1 mol Fe/ 2 mol Fe
• 3 mol MgO / 2 mol Fe

2Na + 2H₂O → 2NaOH+ H₂
How many grams of hydrogen are produced if 120 g of Na are available?

• 5.2 g
• 2.6 g
• 690 g
• 45 g

If a chemist calculates the amount of product that could be obtained in a chemical reaction using stoichiometry, he or she is calculating the

• theoretical yield

• mole ratio

• actual yield

• percentage yield

What is the measured amount of a product obtained from a chemical reaction?

• mole ratio
• theoretical yield
• percentage yield
• actual yield

A chemist interested in the efficiency of a chemical reaction would calculate the

• mole ratio
• rate of reaction
• percent yield
• energy released

What is a Excess Reagent?

• amount you end with
• what you run out of first
• what you have left over
• what you start with

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop

WO₃ + H₂ --> W + H₂O
What coefficient goes in front of H₂?

• 1
• 2
• 3
• 4

Mole ratios are obtained from the

• balanced chemical equation
• periodic table
• molar mass