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Cfe Chem

Total questions: 20

Worksheet time: 2hrs 40mins

Name
Class
Date
1.
The ______________ yield is the maximum amount of product possible in a reaction. This determines the amount of product that should be produced in a perfect setting
a)
Percent
b)
actual
c)
stoichiometry
d)
theoretical
2.

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%

3.
Theoretical yield = 73g
Actual yield = 62g
Calculate the percent yield.
a)
1.16%
b)
116%
c)
85%
d)
76%
4.
In a lab, a scientist calculate 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%
b)
0.82%
c)
10.1 %
d)
100%
5.
Balance the following reaction :
 
CaC₂(s)   +   H₂O(l)   -->   C₂H₂(g)   +   Ca(OH)₂(aq)
a)
1,2,2,2
b)
1,2,1,1
c)
2,1,1,1
d)
2,1,2,1
6.
Using the following equation:
Fe2O3(s) + 3H2(g) → 2Fe(s) + 3H2O(l)
How many moles of iron can be made from  6 moles H2
a)
4 moles Fe
b)
6 moles Fe
c)
9 moles Fe
d)
2 moles Fe
7.
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
8.

Theoretical yield = 146g

Actual yield = 23.5g

Calculate the percentage yield.

a)

1.16%

b)

116%

c)

25%

d)

34%

9.

Reactant and products might stick to containers, be spilled or inhaled causing actual yield to be less than theoretical yield.

a)

true

b)

false

10.

Competing reactions might occur forming other products causing your actual yield to be less than your theoretical yield.

a)

true

b)

false

11.

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

a)

true

b)

false

12.
N2 +  3H2 → 2NH3 
How many moles of hydrogen are needed to react with 2 moles of nitrogen?
a)
6
b)
2
c)
3
d)
1
13.
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
14.

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.

15.
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
16.
7. The amount of product that actually forms when a chemical reaction is carried out in a laboratory is called the _________ yield.
a)
actual
b)
theoretical
c)
percent
17.

Atom economy is equal to

a)

Total mass of products / Mass of Reactants

b)

Mass of desired products / Total mass of Reactants

c)

Reactants / Mass of desired products

d)

Total mass of Reactants / Excess reactant

18.

Calculate the atom economy for the Haber process;

N2 + 3H2 --> 2NH3

a)

16.7%

b)

82.3%

c)

85%

d)

100%

19.

Calculate the atom economy for making Calcium Oxide from Calcium Carbonate;

CaCO3 --> CaO + CO2

a)

32%

b)

74%

c)

56%

d)

40%

20.

Calculate the percentage yield if a 2 step industrial process returns a 60% yield in step 1, followed by a 90% yield in step 2

a)

30%

b)

54%

c)

90%

d)

150%