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LIMITING REACTANT & PERCENTAGE YIELD

Total questions: 25

Worksheet time: 56mins

Name
Class
Date
1.

The limiting reactant is the reactant that __________ .

a)

slows down the reaction

b)

used up first

c)

left over at the end of reaction

d)

controls the speed of the reaction

2.

Theoretical yield = 73g

Actual yield = 62g

Calculate the percent yield.

a)

17.7%

b)

117.7%

c)

84.9%

d)

15.1%

3.

What is a limiting reactant?

a)

The reactant that determines how much product can be made

b)

The reactant that is in excess

c)

The product that you can make the most of

d)

The amount of reactants that react with each other

4.

You need 2 pieces of bread, 1 tablespoon of peanut butter and 2 tablespoons of starwberry jelly to make a sandwich. If you have 10 pieces of bread, 4 tablespoons of peanut butter and 15 tablespoons of jelly, what is the limiting reactant?

a)

bread

b)

strawberry jelly

c)

peanut butter

5.
2H2   +   O2  →  2H2O
How many moles of water can be produced if 8 moles H2 are used?
a)
4 moles
b)
8 moles
c)
16 moles
d)
2 moles
6.

This is what you call a reactant that you have enough of. The one that DOES NOT run out.

a)

Limiting Reactant

b)

Excess Reactant

c)

Highly Reactant

d)

Super Reactant

7.

1 Body + 4 Tires → 1 Car

How many cars can you make with 92 tires and 34 bodies?

a)

23

b)

34

c)

68

d)

46

8.
What is the theoretical yield?
a)
the maximum amount of product from a reaction
b)
the amount of product recovered from a lab experiment
c)
amount of product that causes the reaction to stop
d)
the amount of product needed to reverse the reaction
9.

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

a)

theoretical yield

b)

limiting reactant

c)

actual yield

d)

percentage yield

e)

excess reactant

10.

In a lab, a scientist calculated that he should produce 12.3 grams of product in his experiment. When he is finished collecting his product it weighs 10.1 grams. What is his percent yield?

a)

82.1%

b)

22.8%

c)

18.7%

d)

12.2%

11.
If the percentage yield for a chemical reaction is 80.0%, the 
a)
actual yield is 80.0g for every theoretical yield of 100g.
b)
actual yield is 80 times as much as the theoretical yield.
c)
theoretical yield is 80 times as much as the actual yield. 
d)
theoretical yield is 80.0 g for every actual yield of 100g.
12.

In a balanced equation, the ratio between the coefficient of any two substances is called the _______.

a)

mole ratio

b)

stoichiometry

c)

limiting reactant

d)

excess reactant

13.

Calculate the theoretical yield if given the actual yield and percent yield are 51.4g and 77.0% respectively.

a)

25.6g

b)

1.5g

c)

15g

d)

66.8g

14.

What is the actual yield?

a)

the maximum amount of product from a reaction

b)

the amount of product recovered from a lab experiment

c)

amount of product that causes the reaction to stop

d)

the amount of product needed to reverse the reaction

15.

Some product may be lost during filtering causing your actual yield to be less than your theoretical yield.

a)

true

b)

false

16.

In the image, which reactant is limiting?

a)

The white molecules, because there are extra.

b)

The black atoms, because they are completely used up.

c)

The white molecules, because they are completely used up.

d)

The black atoms, because there are extra.

17.

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

a)

Theoretical yield

b)

Mole ratio

c)

Actual yield

d)

Percentage yield

18.

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

a)

Mole ratio

b)

Theoretical yield

c)

Percentage yield

d)

Actual yield

19.

In a lab, a scientist calculated that he should produce 12.3 grams of product in his experiment. When he is finished collecting his product, it weighs 10.1 grams. What is his percent yield?

a)

82.1%

b)

0.82%

c)

10.1%

d)

122%

20.

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

a)

Mole ratio

b)

Rate of reaction

c)

Percent yield

d)

Energy released

21.

What is an excess reactant?

a)

Substance you end with

b)

Substance that determines the rate of reaction

c)

Substance that is not used up completely

d)

Substance that is used up completely

22.
When does a chemical reaction stop?
a)
When the lab is finished
b)
When the excess reactant is used up
c)
When the limiting reactant is used up
d)
Chemical reactions never stop
23.

When reacting Na with Cl2, we calculated that the theoretical yield should be 13 grams. Our actual yield was 12.5 grams. What is the percent yield?

a)

90.4%

b)

104%

c)

96.15%

d)

1.04%

24.

Reactant and products might adhere to containers causing actual yield to be less than theoretical yield.

a)

true

b)

false

25.
9. Complete the equation for the percent yield of a chemical reaction:
Percent yield=(________)
÷(________)×100%
a)
actual yield; theoretical yield
b)
theoretical yield; actual yield