Limiting Reagent & Percent Yield Review

1. What is a limiting reagent?

• any reactant used up first in a reaction.
• any reactant left over at the end of a reaction.
• the maximum amount of product formed from a given amount of reactant.
• the purity of the reactant.

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5. Which reactant is the limiting reagent and why?
2H₂(g) + O₂(g)  → 2H₂O(l)

• Hydrogen is the limiting reagent because two moles of hydrogen is required for every one mole of oxygen to produce two water.
• Oxygen is the limiting reagent because two moles of hydrogen is required for every one mole of oxygen to produce two water.

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NGSS.HS-PS1-7

6. What is theoretical yield?

• the maximum amount of product that could be formed from a given amount of reactant.
• the amount of product that actually forms when a chemical reaction is carried out in a laboratory.
• the efficiency of a particular chemical reaction within the respective conditions.
• the reactant that is used up first in a reaction.

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NGSS.HS-PS1-7

7. The amount of product that actually forms when a chemical reaction is carried out in a laboratory is called the _________ yield.

• actual
• theoretical
• percent

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NGSS.HS-PS1-7

True or False?
The actual yield is usually greater than the theoretical yield.

• False
• True

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NGSS.HS-PS1-7

2 Al + 3 Cl₂ ---> 2 AlCl₃.

If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

• AlCl3

• Cl2

• Al

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NGSS.HS-PS1-7

4NH₃+6NO --> 5N₂ + 6H₂O

What is the limiting reactant if 10 moles of NH₃ react with 30.0 moles of NO?

• NH₃

• NO

• N₂

• water

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NGSS.HS-PS1-7

Theoretical yield = 73g
Actual yield = 62g
Calculate the percent yield.

• 1.16%
• 116%
• 85%
• 76%

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NGSS.HS-PS1-7

4NH₃ + 5O₂ --> 4NO + 6H₂O

How many Liters of NO are formed if 6.30g of ammonia react with 1.80g of oxygen?

• 1.5 L

• 2.02 L

• 1.01 L

• 8.30 L

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NGSS.HS-PS1-7

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

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

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NGSS.HS-PS1-7