AnswersLA-Chemistry AIntroduction to Stoichiometry

Introduction to Stoichiometry — Unit test Answers

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The equation for water is H2 +O2 → H2O. To balance the equation, which coefficient should be placed in front of H2 and H2O?

A
1
B
2
C
3
D
4
2
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Consider the balanced equation below. What is the mole ratio of PCl3 to PCl5?

Question illustration
A
1:1
B
2:1
C
3:5
D
5:3
3

Consider the reaction below.2Al2O3 4Al + 3O2How many moles of oxygen are produced if 11.0 mol of Al are produced?

Question illustration
A
8.25 mol
B
11.0 mol
C
14.7 mol
D
16.5 mol
4

Which statement best describes the difference between endothermic and exothermic reactions?

A
They are opposites because endothermic reactions require energy and exothermic reactions release energy.
B
They are opposites because endothermic reactions release energy and exothermic reactions require energy.
C
They the same because they are both ways of forming precipitates.
D
They the same because they are both ways of forming gasses.
5

Nio conducts a science experiment. He puts yeast into a bottle with water and sugar, and then caps the bottle with a balloon. He returns two hours later and notices there are bubbles on the surface of the mixture in the bottle and that the balloon has inflated, but there are no other apparent changes.

A
a non-chemical change, because there are no indicators of chemical changes taking place
B
a chemical change, because the mixture changed color
C
a chemical change, because a gas was produced
D
a non-chemical change, because the changes that occurred are reversible
6

When balanced, which equation would have the coefficient 3 in front of any of the reactants?

A
Zn + HCl ZnCl2 + H2
Option A
B
H2SO4 + B(OH)3 B2(SO4)3 + H2O
Option B
C
Fe + AgNO3 Fe(NO3)2 + Ag
Option C
D
C2H4O2 + O2 CO2 +H2O
Option D
7

[BLANK]

A
synthesis
B
polymerization
C
decomposition
D
oxidation
E
replacement
8

What else is produced during the replacement reaction of magnesium and hydrochloric acid?Mg + 2HCl H2 + ________

Question illustration
A
MgCl2
B
Mg2Cl2
C
Mg2Cl
D
MgCl
9

Which statement best describes balancing equations and the law of conservation of mass?

A
There are more atoms in the reactants than in the products, and the total mass is the same in the reactants and in the products.
B
The number of atoms is the same in the reactants and in the products, and the total mass is the same in the reactants and in the products.
C
There are fewer atoms in the reactants than in the products, and the total mass is less in the reactants than in the products.
D
There are more atoms in the reactants than in the products, and the total mass is higher in the reactants than in the products.
10

Which type of reaction is Mg + S → MgS?

p
polymerization
s
synthesis
r
replacement
d
decomposition
11

Which represents an endothermic reaction?

A
wood burning in a fire
B
splitting a gas molecule
C
using a heat pack on an injury
D
TNT exploding
12

Ciara’s bike has rusted, which means that the iron in the metal changed to rust.

A
an energy formation
B
an exothermic reaction
C
a chemical reaction
D
a precipitate formation
13

Consider the equation below.Zn + H2SO4 ZnSO4 + H2The mole ratio of zinc to zinc sulfate is

Question illustration
A
1:1.
B
1:2.
C
2:1.
D
3:1.
14

The following balanced equation shows the formation of sulfur dioxide.S + O2 SO2How many moles of sulfur are needed to produce 15.0 mol of sulfur dioxide?

Question illustration
A
7.50 mol
B
10.5 mol
C
15.0 mol
D
30.0 mol
15

What is produced during the replacement reaction of Cu(NO3)2 and Zn?

A
ZnNO3 + Cu
B
Zn + Cu(NO3)2
C
ZnCu + 2NO3
D
Zn(NO3)2 + Cu
16

In what ways is this study group working effectively together? Check all that apply.

A
structuring their study sessions well
B
using good listening skills
C
having thoughtful discussions
D
sharing their notes freely with each other
E
showing a commitment to the group
17

What three things should study groups do to ensure they are productive?

Answer:

To ensure they are productive, study group members should participate actively in discussions, practice good listening skills, and follow established group rules or guidelines.

18

Which students experience the benefits of a study group? Check all that apply.Lena, who sees new viewpoints on a topicYuron, who lets others do all the workRoni, who uses the time to multitaskAdi, who better recalls what he has learnedYuto, who understands lessons betterRiko, who looks forward to learning more

A
Lena, who sees new viewpoints on a topic
B
Yuron, who lets others do all the work
C
Roni, who uses the time to multitask
D
Adi, who better recalls what he has learned
E
Yuto, who understands lessons better
F
Riko, who looks forward to learning more
19

The first chart shows the effect of the normal breakdown of material from reactants to products. The second chart shows the same reaction but with an added modification.

Question illustration
A
Reaction A has an enzyme.
B
Reaction B has an enzyme.
C
Reaction A has an inhibitor.
D
Reaction B has an inhibitor.
20

Sample Response: In productive study groups, members participate actively in the discussions, use good listening skills, and follow group guidelines. What did you include in your response? Check all that apply. participate activelyuse good listening skillsfollow rules or guidelines

A
participate actively
B
use good listening skills
C
follow rules or guidelines

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