Question 1

Which of the following best describes a combustion reaction?

Accepted Answer

A reaction in which a substance combines with oxygen to form one or more oxygen-containing compounds and emits heat.

Question 2

What is the correct balanced chemical equation for the combustion of methane?

Accepted Answer

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

Question 3

In the balanced equation $$\mathrm{2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)}$$, how many moles of $$\mathrm{CO_2$}$$ are produced from 22.0 moles of $$\mathrm{C_8H_{18}}$$?

Accepted Answer

$$176$$ moles

Question 4

Which law is demonstrated by the need to balance chemical equations?

Accepted Answer

Law of Conservation of Mass

Question 5

Given the balanced equation $$\mathrm{4FeCO_3(s) + O_2$(g) \rightarrow 2Fe_2O_3(s) + 4CO_2(g)}$$, how many iron atoms are present on the right-hand side?

Accepted Answer

4

Question 6

Which of the following is NOT provided by a chemical equation?

Accepted Answer

The speed at which the reaction occurs

Question 7

If you have 10 cups of cheese and the pizza recipe requires 2 cups of cheese per pizza, how many pizzas can you make?

Accepted Answer

5 pizzas

Question 8

In the reaction $$\mathrm{2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)}$$, what is the stoichiometric ratio of $$\mathrm{O_2$} to$$ $$\mathrm{CO_2$}$$?

Accepted Answer

$$\dfrac{25}{16}$$

Question 9

Which abbreviation correctly represents an aqueous solution in a chemical equation?

Accepted Answer

$$(aq)$$

Question 10

A student writes the equation $$\mathrm{CH_4$(g) + O_2$(g) \rightarrow CO_2$(g) + H_2O(g)}. $$What is wrong with this equation?

Accepted Answer

It is not balanced; the number of hydrogen atoms is not equal on both sides.

Question 11

Which step is necessary to balance a chemical equation?

Accepted Answer

Change the coefficients in front of the compounds.

Question 12

If 2 moles of $$\mathrm{C_8H_{18}}$$ react with excess $$\mathrm{O_2$}$$, how many moles of $$\mathrm{H_2O}$$ are produced according to $$\mathrm{2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)}$$?

Accepted Answer

18 moles

Question 13

What is the term for the numerical relationship between chemical quantities in a chemical reaction?

Accepted Answer

Stoichiometry

Question 14

Which of the following is a correct mole-to-mole conversion factor from the equation $$\mathrm{2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)}$$?

Accepted Answer

$$\dfrac{16\ \mathrm{mol}\ CO_2$}{2\ \mathrm{mol}\ C_8H_{18}}$$

Question 15

Why must the coefficients in a chemical equation be adjusted rather than the subscripts?

Accepted Answer

Changing coefficients alters the number of molecules, while changing subscripts changes the identity of the compounds.

Question 16

A reaction produces 10 moles of $$\mathrm{CO_2$}$$ from the combustion of $$\mathrm{C_8H_{18}}. $$How many moles of $$\mathrm{C_8H_{18}}$$ were burned?

Accepted Answer

Question 17

Which of the following is a real-world application of stoichiometry?

Accepted Answer

Calculating the amount of carbon dioxide emitted from burning gasoline in a car.

Question 18

In the equation $$\mathrm{CH_4$(g) + 2O_2(g) \rightarrow CO_2$(g) + 2H_2O(g)}$$, what is the total number of oxygen atoms on the product side?

Accepted Answer

6

Question 19

Which of the following statements about chemical reactions is TRUE?

Accepted Answer

Chemical reactions involve changes in matter resulting in new chemical substances.

Chemical Reactions and Chemical Quantities: Equations and Stoichiometry

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