AnswersAZ-Physical Science A-CRLab: Rate of Chemical Reactions

Lab: Rate of Chemical Reactions — Unit test Answers

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1
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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
2
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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
3

What is a limitation of using a chemical formula, such as C6H12O6, to represent a compound?

A
The chemical formula does not show the types of elements that make up the compound.
B
The chemical formula does not show how the atoms are connected to one another.
C
The chemical formula does not show the number of atoms of each element in a molecule.
D
The chemical formula does not show the chemical symbols of the elements in the compound.
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

Lars is balancing equations with his study group. He is unsure about one equation because each member of the study group came up with a different answer. Which is the proper way to balance the equation Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O?

A
Ca(OH)2 + H3PO4 → Ca3(PO4)2 + 6H2O
B
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O
C
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 3H2O
D
Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O
6

How many atoms of each element are in the chemical formula NH4NO3?

A
1 nitrogen, 1 hydrogen, and 3 oxygen
B
1 nitrogen, 4 hydrogen, and 3 oxygen
C
2 nitrogen, 4 hydrogen, and 3 oxygen
D
5 nitrogen, 1 hydrogen, and 1 oxygen
7

This chart lists four kinds of polymers and their sources.What can be known about all four polymers, despite their differences?

Question illustration
A
They come from living things.
B
They share ionic carbon bonds.
C
They are at least 100 monomers long.
D
They are made of repeating subunits.
8

What does the chemical formula C3H6O2 tell about a molecule of the compound it represents?

A
It is made up of 3 atoms of 11 different elements.
B
It is made up of 11 atoms joined in a straight line.
C
It is made up of 11 total atoms of 3 different elements.
D
It is made up of 1 atom composed of 3 different elements.
9

Suna passes an electric current through a sample of clear, colorless, and odorless liquid. As the experiment continues, bubbles form, and the volume of liquid decreases. Suna collects samples of two colorless, odorless gases that bubble out of the liquid. One of the gases burns. Neither the original liquid nor the other gas burns.Which is the best explanation of her results?

A
The electric current changed some of the sample to gas even though the sample was not breaking down. Therefore, the original liquid is a compound.
B
The electric current released a gas that was odorless and colorless, like the original sample. Therefore, the original liquid is an element.
C
The sample was broken down by the electric current and formed a new substance that could burn. Therefore, the original liquid is a compound.
D
The sample lost some of its volume, but the gas still had the same chemical makeup as the original sample. Therefore, the original liquid is an element.
10

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
11

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
12

Why do natural polymers not pose as much of an issue in landfills as synthetic polymers?

A
Natural polymers are cheap to recycle, and synthetic polymers are expensive to recycle.
B
Natural polymers are expensive to recycle, and synthetic polymers are cheap to recycle.
C
Natural polymers are not biodegradable, and synthetic polymers are biodegradable.
D
Natural polymers are biodegradable, and synthetic polymers are not biodegradable.
13

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
14

Eugene works at a carpet factory. Which natural polymer does he most likely work with to make the carpets?

A
wool
B
rubber
C
nylon
D
silk
15

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.

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