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Limiting Reactants and Stoichiometry

Total questions: 26

Worksheet time: 44mins

Name
Class
Date
1.

What is the definition of a limiting reactant in a chemical reaction?

a)

The substance that is completely used up first in a reaction.

b)

The substance that is left over after a reaction.

c)

The substance that controls the rate of the reaction.

d)

The substance that is used to catalyze the reaction.

2.

In the reaction 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O , if you start with 3 moles of H2H_2 and 1 mole of O2O_2 , which is the limiting reactant?

a)

H2H_2

b)

O2O_2

c)

Both are limiting.

d)

Neither is limiting.

3.

Which is an attribute of the excess reactant in a chemical reaction?

a)

It increases the reaction rate.

b)

It is completely used up during the reaction.

c)

It remains after the limiting reactant is used up.

d)

It decreases the yield of the product.

4.

Calculate the amount of water produced when 4 moles of H2H_2 react with 4 moles of O2O_2 in the reaction 2H2+O2→2H2O2H_2 + O_2 \rightarrow 2H_2O .

a)

4 moles of H2OH_2O

b)

8 moles of H2OH_2O

c)

2 moles of H2OH_2O

d)

6 moles of H2OH_2O

5.

If 5 moles of nitrogen react with 15 moles of hydrogen according to the equation N2+3H2→2NH3N_2 + 3H_2 \rightarrow 2NH_3 , how many moles of ammonia are produced?

a)

5 moles

b)

10 moles

c)

15 moles

d)

20 moles

6.

In a reaction where A+2B→CA + 2B \rightarrow C , you start with 4 moles of A and 10 moles of B. How many moles of B will be left unreacted after the reaction goes to completion?

a)

2 moles

b)

4 moles

c)

6 moles

d)

8 moles

7.

Given the reaction 3Fe+4O2→2Fe2O33Fe + 4O_2 \rightarrow 2Fe_2O_3 , if you start with 10.0 moles of FeFe and 6.0 moles of O2O_2 , which reactant is in excess and by how much?

a)

FeFe is in excess by 5.5 moles.

b)

O2O_2 is in excess by 2 moles.

c)

FeFe is in excess by 4.5 mole.

d)

O2O_2 is in excess by 1 mole.

8.

For the balanced chemical equation 2A+3B→4C2A + 3B \rightarrow 4C , if 10. moles of A react with 10. moles of B, how many moles of C will be produced?

a)

10. moles

b)

13 moles

c)

17 moles

d)

20. moles

9.

In the reaction 6K+N2→2K3N6K + N_2 \rightarrow 2K_3N , if 12 moles of K and 10. moles of N2 are used, how many moles of K3N are formed?

a)

4.0 moles

b)

6.0 moles

c)

8.0 moles

d)

10. moles

10.

Given the equation 2X+Y→Z2X + Y \rightarrow Z , if you start with 50 grams of X and 20 grams of Y, and the molar mass of X is 10 g/mol and Y is 5 g/mol, which is the limiting reactant?

a)

X

b)

Y

c)

Both are limiting.

d)

Neither is limiting.

11.

In a reaction where 3Mg+N2→Mg3N23Mg + N_2 \rightarrow Mg_3N_2 , you start with 15 grams of Mg and 10 grams of N2. The molar mass of Mg is 24.3 g/mol and N2 is 28 g/mol. How many grams of Mg3N2 can be produced?

a)

21 grams

b)

25 grams

c)

30 grams

d)

35 grams

12.

For the reaction 2S+3T→4U2S + 3T \rightarrow 4U , if you start with 200 grams of S and 300 grams of T, and the molar mass of S is 32 g/mol and T is 48 g/mol, identify the limiting reactant.

a)

S

b)

T

c)

Both are limiting.

d)

Neither is limiting.

13.

A reaction 2A+4B→3C2A + 4B \rightarrow 3C is set up with 8 moles of A and 8 moles of B. Calculate the amount of C produced and identify the excess reactant.

a)

12 moles of C, A is in excess

b)

12 moles of C, B is in excess

c)

6 moles of C, A is in excess

d)

6 moles of C, B is in excess

14.

Use the equation 2 Al + 3 Cl2 ---> 2 AlCl3. If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

a)

AlCl3

b)

Cl2

c)

Al

15.
The limiting reactant
a)
slows the reaction down
b)
is used up first
c)
is the reactant that is left over
d)
controls the speed of the reaction
16.
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
17.

1 Cheese + 2 Bread --> 1 grilled cheese

How many grilled cheeses can you make with 26 slices of bread and 14 pieces of cheese?

a)

14

b)

13

c)

26

18.
Which pair has the same empirical formula?
a)
NaCrO4 and Na2Cr2O7
b)
C2H4O2 and C6H12O6
c)
C3H6O3 and C2H6O2
d)
CH4 and C2H6
19.
What is the empirical formula of the following molecular formula:  C3H6
a)
C3H6
b)
CH2
c)
C2H4
d)
CH3
20.
A substance has a molecular formula of C8H10N4O2. The empirical formula is 
a)
CHNO
b)
C2H6N2O
c)
C4H5N2O
d)
C9H7N3O
21.
Find the percent composition of Cu2S?
a)
%Cu= 67.987 %S= 32.013
b)
%Cu= 79.854   %S= 20.145
c)
%Cu= 35.946   %S= 64.054
22.

Which element has an abundance of 39.04% in the compound sodium phosphate, Na3PO4

a)

Na

b)

P

c)

O

d)

None of the above

23.

Which statement best describes the excess reactant in a chemical reaction?

a)

It remains after the limiting reactant is used up.

b)

It is always present in equal amounts as the limiting reactant.

c)

It is completely consumed during the reaction.

d)

It determines the amount of product formed.

24.

​ (a)   ---->​ (b)  

The limiting and excess reactant will be on the ​ (c)   side of the equation.

Choose from the below words
Reactants
Products
left
right
25.

Students held a four-mole strip of magnesium over a flame until a combustion began. Students were provided the balanced chemical reaction for the combustion of magnesium and asked to describe the limiting reactant. 

2Mg + O2 → 2MgO

a)

Student 1

b)

Student 2

c)

Student 3

d)

Student 4

26.

Identify the limiting and excess reactants in the reaction shown.

a)

N2 is limiting and H2 is excess. 

b)

H2 is limiting and N2 is excess. 

c)

NH3 is both limiting and excess.

d)

There is no limiting reactant.