Question 1

Which of the following best describes the Law of Conservation of Matter as it applies to chemical reactions?

Accepted Answer

The total number of atoms of each element must be the same on both sides of a chemical equation.

Question 2

Given the balanced equation $\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}$, how many moles of $\mathrm{CO_2}$ are produced from 32 g of $\mathrm{CH_4}$? (Molar mass of $\mathrm{CH_4}$ = 16 g/mol)

Accepted Answer

2 moles

Question 3

Which of the following is a balanced chemical equation?

Accepted Answer

$\mathrm{Fe_2O_3 + 3C \rightarrow 4Fe + 3CO_2}$

Question 4

A reaction in which two or more simple substances combine to form a more complex substance is called:

Accepted Answer

Synthesis (Combination)

Question 5

Which of the following reactions is a combustion reaction?

Accepted Answer

$\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}$

Question 6

In the reaction $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$, how many grams of $\mathrm{H_2O}$ are produced from 16.0 g of $\mathrm{O_2}$? (Atomic mass: H = 1 g/mol, O = 16 g/mol)

Accepted Answer

36 g $\mathrm{H_2O}$

Question 7

Which type of reaction is represented by $\mathrm{2H_2O \rightarrow 2H_2 + O_2}$?

Accepted Answer

Decomposition

Question 8

A student mixes aqueous solutions of $\mathrm{Pb(NO_3)_2}$ and $\mathrm{NaI}$ and observes a yellow solid forming. What type of reaction is this?

Accepted Answer

Precipitation (Double Replacement)

Question 9

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction in which heat is a product.

Question 10

In the reaction $\mathrm{Zn + CuCl_2 \rightarrow ZnCl_2 + Cu}$, which element is oxidized?

Accepted Answer

Zn

Question 11

If you have 48 g of $\mathrm{O_2}$, how many grams of $\mathrm{CO_2}$ will you make according to the reaction $\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}$? (Molar mass: $\mathrm{O_2}$ = 32 g/mol, $\mathrm{CO_2}$ = 44 g/mol)

Accepted Answer

33 g

Question 12

Which of the following is a redox reaction?

Accepted Answer

$\mathrm{Zn + CuCl_2 \rightarrow ZnCl_2 + Cu}$

Question 13

Which of the following best describes a double replacement reaction?

Accepted Answer

Two elements switch places in two compounds.

Question 14

A reaction in which an acid reacts with a base to form water and a salt is called:

Accepted Answer

Neutralization

Question 15

Which of the following is an example of an endothermic reaction?

Accepted Answer

Cooking an egg

Question 16

In the reaction $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$, if you start with 4 moles of $\mathrm{H_2}$ and excess $\mathrm{O_2}$, how many moles of $\mathrm{H_2O}$ will be produced?

Accepted Answer

4 moles

Question 17

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 18

A student starts with 52 g of $\mathrm{H_2O}$ produced in the reaction $\mathrm{CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O}$. How many moles of $\mathrm{CH_4}$ did they start with? (Molar mass $\mathrm{H_2O}$ = 18 g/mol)

Accepted Answer

1.44 moles

Question 19

Which of the following best describes a single replacement reaction?

Accepted Answer

One element replaces another in a compound.

Question 20

Which of the following is the correct classification and energy change for the reaction $\mathrm{CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq) + heat}$?

Accepted Answer

Synthesis, exothermic

Chap5 Chemical Reactions: Classification, Balancing, and Stoichiometry

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