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WorksheetsLimiting and Excess Reactants and Percent Yield
Total questions: 28
Worksheet time: 45mins
Name
Class
Date
1.
The limiting reactant
a)
.
b)
is used up first
c)
is the reactant that is left over
d)
.
2.
The excess reactant
a)
.
b)
is used up first
c)
is the reactant that is left over
d)
.
3.
1 Body + 4 Tires --> 1 car
How many cars can you make with 92 tires and 34 bodies?
How many cars can you make with 92 tires and 34 bodies?
a)
23
b)
34
c)
68
d)
46
4.
1 Body + 4 Tires --> 1 car
How many cars can you make with 92 tires and 34 bodies?
In this senario the tires would be the _____________ reactant.
How many cars can you make with 92 tires and 34 bodies?
In this senario the tires would be the _____________ reactant.
a)
Limiting
b)
Excess
5.
When the limiting reactant is used up, what happens?
a)
the reaction speeds up
b)
the reaction slows down
c)
the reaction moves to its 2nd stage
d)
the reaction stops
6.
What are the correct steps for determining the limiting reactant?
a)
divide each reactant by its molar mass and look for the smallest number
b)
balance the chemical equation and look for the smallest coefficient
c)
divide the moles of each reactant by its coefficient and look for the smallest number
d)
divide each reactant by Avogadro's number and look for the smallest number
7.
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
8.
True or False?
A chemical reaction stops before the limiting reagent is used up.
A chemical reaction stops before the limiting reagent is used up.
a)
True
b)
False
9.
When does a reaction stop?
a)
When it wants to
b)
When both the limiting and excess reactants are gone
c)
When all the excess reactant has been consumed
d)
When all the limiting reactant has been consumed
10.
What is the limiting reactant if 10 moles of NH3 react with 30.0 moles of NO?
4NH3+6NO --> 5N2 + 6H2O
4NH3+6NO --> 5N2 + 6H2O
a)
NH3
b)
NO
c)
N2
d)
water
11.
What is the limiting reactant if 15 moles of NH3 react with 16 moles of NO?
4NH3+6NO --> 5N2 + 6H2O
4NH3+6NO --> 5N2 + 6H2O
a)
NH3
b)
NO
c)
N2
d)
water
12.
*Look back at preceding question. * What is the limiting reactant if 15 GRAMS of NH3 react with 16 GRAMS of NO?
4NH3+6NO --> 5N2 + 6H2O
(Remember, convert grams to moles, then divide each substance by the number of moles given as the coefficient from the balanced chemical equation).
4NH3+6NO --> 5N2 + 6H2O
(Remember, convert grams to moles, then divide each substance by the number of moles given as the coefficient from the balanced chemical equation).
a)
NH3 is the limiting because the reaction only requires 0.22 mol of NH3
b)
NO is the limiting reactant because the reaction only requires 0.088 mol NO
c)
NH3 is the limiting because the reaction only requires 0.88 mol of NH3
d)
NO is the limiting reactant because the reaction only requires 0.53 mol NO
13.
The Formula to make S'mores is:
2C + 1M + G2 → C2MG2. If you have 5 Marshmallows (M), 9 Chocolate Pieces (C), and 9 Graham Cracker Halves (G), how many S'mores can you make?
2C + 1M + G2 → C2MG2. If you have 5 Marshmallows (M), 9 Chocolate Pieces (C), and 9 Graham Cracker Halves (G), how many S'mores can you make?
a)
5
b)
4
c)
8
d)
42
14.
True or False?
The actual yield is usually greater than the theoretical yield.
The actual yield is usually greater than the theoretical yield.
a)
False
b)
True
15.
Mole ratios are obtained from the
a)
balanced chemical equation
b)
periodic table
c)
molar mass
16.
What is stoichiometry?
a)
The study of how the quantities of reactants and products are related in chemical reactions
b)
The study of the speed of reactions
c)
The study of how chemical reactions occur
d)
The study of types of reactions
17.
Stoichiometry is based on the law of conservation of
a)
charge
b)
mass
c)
reactants
d)
volume
18.
In a balanced equation, the ratio between the coeffients of any two substances is called the _______.
a)
mole ratio
b)
stoichiometry
c)
limiting reactant
d)
excess reactant
19.
The study of quantitative relationships between the amounts of reactants used and products formed by a chemical reaction; is based on the law of conservation of mass
a)
percent yield
b)
stoichiometry
c)
mole ratio
d)
limiting reactant
20.
A reactant that remains after a chemical reaction stops
a)
stoichiometry
b)
mole ratio
c)
excess reactant
d)
limiting reactant
21.
A reactant that is totally consumed during a chemical reaction, limits the extent of the reaction, and determines the amount of product
a)
stoichiometry
b)
mole ratio
c)
excess reactant
d)
limiting reactant
22.
To determine the limiting reactant in a chemical reaction, one must know the
a)
amount of product formed
b)
available amount of one of the reactants
c)
available amount of each of each reactant
d)
speed of the reaction
23.
The coefficients in a chemical equation represent the
a)
number of atoms in each compound in a reaction
b)
relative numbers of moles of reactants and products
c)
masses, in grams, of all reactants and products
d)
number of valence electrons involved in the reaction
24.
A chemical reaction involving substances A and B stops when B is completely used. B is the
a)
excess reactant
b)
primary reactant
c)
limiting reactant
d)
primary product
25.
Stoichiometry is based on _____________.
a)
the law of constant ratios
b)
Avogadro's constant
c)
law of conservation of mass
d)
percent composition
26.
Mole ratios are obtained from the ________________.
a)
balanced chemical equation
b)
molar masses
c)
periodic table
d)
subscripts
27.
What is the first thing you must do to solve a stoichiometric problem?
a)
find the excess reactant
b)
find the limiting reactant
c)
find the empirical formula
d)
write a balanced chemical equation
28.
How do you determine the limiting reactant?
a)
Find the amount of product produced by each amount of reactant. The reactant that makes the most is the limiting reactant.
b)
Find the amount of product produced by each amount of reactant. The reactant that makes the least is the limiting reactant.
c)
The reactant with the least amount of mass (grams) present is the limiting reactant.
d)
Cannot be determined.
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