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Stoichiometry & % Yield practice

Total questions: 15

Worksheet time: 41mins

Name
Class
Date
1.

What is the first thing you must have to solve a stoichiometry problem?

a)

a Balanced Equation

b)

the amount of product formed

c)

an Unbalanced Equation

d)

the actual amounts of all reactants

2.
WO3 + H2 --> W + H2O
What coefficient goes in front of H2?
a)
1
b)
2
c)
3
d)
4
3.
True or False. You must convert grams to moles to do stoichiometry.
a)
True
b)
False
4.

2H2 + O2 → 2H2O

If 8 moles H2 are reacted with excess oxygen, what is the theoretical yield of water, in moles?

a)

4 moles

b)

8 moles

c)

16 moles

d)

2 moles

5.
2H2  +   O2  →  2H2O
How many moles of oxygen are consumed if 8 moles H2 are used?
a)
2
b)
4
c)
6
d)
8
6.

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

a)

3mol Mg / 2 mol Fe

b)

2 mol Mg/ 3 mol Fe

c)

1 mol Fe/ 2 mol Fe

d)

3 mol MgO / 2 mol Fe

7.

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

a)

3mol Mg / 2 mol Fe

b)

2 mol Mg/ 3 mol Fe

c)

1 mol Fe/ 2 mol Fe

d)

3 mol MgO / 2 mol Fe

8.

2 KClO3 → 2 KCl + 3 O2

How many moles of oxygen can be produced when 6.7 moles of KClO3 decompose completely?

a)

6.7 mol

b)

1.0 mol

c)

10.1 mol

d)

4.5 mol

9.

2Na + 2H2O → 2NaOH+ H2

What is the theoretical yield of hydrogen if 120 g of Na are available?

a)

5.3 g

b)

2.6 g

c)

690 g

d)

45 g

10.

CH4 + 2 O2 → CO2 + 2 H2O

If 5.39 moles of carbon dioxide are produced from the combustion of 110 g of CH4, what is the percent yield?

a)

38.3 %

b)

6.85 %

c)

6.11 %

d)

78.7 %

11.

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)

mole ratio

c)

actual yield

d)

percentage yield

12.

2Al + 3H2SO4 -> Al2(SO4)3 + 3H2

If 208.2 g grams of aluminum sulfate is formed from the reaction of 250g H2SO4 with excess aluminum, what is the percent yield?

a)

85.0 %

b)

71.5 %

c)

45.0 %

d)

64.2 %

13.
What does percent yield indicate?
a)
The amount of product we should get
b)
The efficiency of the lab
c)
The amount of product we actually got
d)
nothing
14.
Theoretical yield = 73g
Actual yield = 62g
Calculate the percent yield.
a)
1.16%
b)
116%
c)
85%
d)
76%
15.

2 Fe2O3 + 3C → 4Fe + 3CO2

You react 28 grams of carbon with sufficient iron (III) oxide and obtain 99.6 grams of CO2. What is the percent yield of CO2?

a)

28.1 %

b)

209.2 %

c)

64.4 %

d)

97.1 %