AnswersHS Physical Science A - CR Summer School 2026Lab: Rate of Chemical Reactions

Lab: Rate of Chemical Reactions — Unit test Answers

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1
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What are the products of the combustion of a hydrocarbon?

A
carbon and oxygen
B
carbon dioxide and water
C
carbon and hydrogen
D
carbon dioxide and hydrogen
2
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Which type of reaction has the general formula of AB + CD → AD + CB?

A
synthesis
B
decomposition
C
oxidation
D
replacement
3

How many chlorine atoms are on the products side of the reaction 2Al + 6HCl → 2AlCl3 + 3H2?

A
2
B
3
C
6
D
9
4

Which best describes a chemical reaction?

A
the rearrangement of atoms by breaking and reforming chemical bonds
B
a reaction that absorbs heat from the surroundings
C
a reaction that releases heat to the surroundings
D
the rearrangement of molecules based on temperature and pressure
5

Which condition must be met in order for an equation to be balanced?

A
The elements in the reactants are the same as the elements in the products.
B
There are fewer elements in the reactants than there are in the products.
C
The number of atoms in the reactants is greater than the number of atoms in the products.
D
The number of atoms in the reactants equals the number of atoms in the products.
6

The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material.

A
an endothermic reaction
B
an energy formation
C
a chemical reaction
D
a precipitate formation
7

Which symbol in a chemical equation separates the reactants from the products?

A
=
B
→
C
>
D
+
8

Which balances the equation Mg + O2 → MgO?

A
Mg + 2O2 → 4MgO
B
2Mg + 2O2 → 2MgO
C
2Mg + O2 → 2MgO
D
2Mg + 2O2 → 4MgO
9

Harvey mixes two liquids. Which observation of the new mixture most likely indicates a precipitate is forming?

A
a cloudy appearance
B
a bubble formation
C
a change in color
D
a change in odor
10

Lexi is balancing equations. She is finding one equation to be very difficult to balance. Which explains how to balance the equation ZnSO4 + Li2CO3 → ZnCO3 + Li2SO4?

A
One reactant and one product needs the coefficient 2.
B
The products both need a 3 coefficient.
C
The reactants both need a 2 coefficient.
D
Atoms in the equation are already in balance.
11

Chemical A and Chemical B react in an exothermic reaction. What can be known about what will happen when Chemical A and Chemical B are mixed together?

A
The old substance will need more energy to break its chemical bonds than the new substance will release.
B
More energy will be released from the old substance than the new substance will release to form its chemical bonds.
C
The color will change as a result of the reaction.
D
The substance will bubble as a result of the reaction.
12

Which clue can be used to identify a chemical reaction as a decomposition reaction?

A
The reaction involves oxygen.
B
The reaction involves ions.
C
The reaction has a single reactant.
D
The reaction has a single product.
13

Hydrochloric acid and sodium hydroxide can be combined to form sodium chloride and water. Which best explains the reaction?

A
The mass of sodium hydroxide will result in the same mass of sodium chloride.
B
The total mass of hydrochloric acid and sodium hydroxide will result in a lower total mass of sodium chloride and water.
C
The mass of hydrochloric acid will result in the same mass of sodium chloride.
D
The total mass of hydrochloric acid and sodium hydroxide will result in the same total mass of sodium chloride and water.
14

What else is produced during the replacement reaction of silver nitrate and potassium sulfate?2AgNO3 + K2SO4 Ag2SO4 + ________

Question illustration
A
KNO3
B
2KNO3
C
K2
D
2AgNO3
15

Which are the products in the equation CH3SH + 4O2 → CO2 + SO2 +2H2O? Check all that apply.

A
CH3SH
B
O2
C
CO2
D
SO2
E
H2O
16

Thirty grams of lead oxide and fifteen grams of ammonia react completely to produce solid lead, nitrogen gas, and liquid water. What will be approximate mass of all three products?

A
10 g
B
15 g
C
45 g
D
450 g
17

The equations are not balanced. Which equation would have the same coefficients in the same order as 2CO2 + 3H20 C2H6O + 3O2?

Question illustration
A
FeCl3 + NH4OH Fe(OH)3 + NH4Cl
Option A
B
CH4 + O2 CO2 + H2O
Option B
C
Fe + H2SO4 Fe2(SO4)3 + H2
Option C
D
PCl5 + H2O HCl + H3PO4
Option D
18

In the product 6O2, what does the coefficient mean?

A
There are 12 molecules of O2,
B
There are 8 molecules of O2,
C
There are 6 molecules of O2.
D
There are 2 molecules of O2.
19

Leslie incorrectly balances an equation as 2C4H10 + 12O2 → 8CO2 + 10H2O.

A
2
B
8
C
10
D
12
20

Which best explains why a firework being ignited is an example of an exothermic reaction and not an endothermic reaction?

A
The fireworks produce colors.
B
The fireworks give off heat.
C
Igniting the fireworks requires energy.
D
Igniting the fireworks makes an odor.

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