Q: Which equation correctly relates moles of reactant A to moles of product B using stoichiometric coefficients?

$$\text{Moles B} = \frac{n_B}{n_A} \times \text{Moles A}$$

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, often emitting heat.

Question 2

What is the balanced chemical equation for the combustion of methane ($$CH_4) in $$oxygen?

Accepted Answer

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

Question 3

In the reaction $$2KCIO_3 \rightarrow 2KCl + 3O_2$$, what type of reaction is this?

Accepted Answer

Decomposition reaction

Question 4

Which statement about balancing chemical equations is correct?

Accepted Answer

The number and types of atoms must be the same on both sides of the equation.

Question 5

Given the reaction $$N_2 + 3H_2$$ \rightarrow 2NH_3$$, how many moles of NH_3$ are produced from 6 moles of H_2$?

Accepted Answer

4 moles

Question 6

A student burns 22.0 moles of $$C_8H_{18} in $$excess $$O_2. $$How many moles of $$CO_2$$ are produced according to the reaction $$2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)$$?

Accepted Answer

176 moles

Question 7

Which of the following is the correct stoichiometric ratio to convert moles of $$C_8H_{18} to $$moles of $$CO_2 in $$the reaction $$2C_8H_{18} + 25O_2 \rightarrow 16CO_2 + 18H_2O$$?

Accepted Answer

$$\frac{8\ mol\ CO_2$}{1\ mol\ C_8H_{18}}$$

Question 8

What is the mass of $$H_2O$$ produced from 1.00 g of $$C_8H_{18} in $$the reaction $$2C_8H_{18}(l) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)$$? (Molar mass: $$C_8H_{18} = 114.224\ g/mol$$, $$H_2O = 18.016\ g/mol)$$

Accepted Answer

1.42 g

Question 9

In a chemical reaction, what is the limiting reactant?

Accepted Answer

The reactant that is completely consumed and determines the amount of product formed.

Question 10

A reaction has a theoretical yield of 12.74 g $$CO_2$$, but only 10.01 g $$CO_2 is $$produced. What is the percent yield?

Accepted Answer

78.57%

Question 11

Which of the following is NOT a step in solving a limiting reactant problem?

Accepted Answer

Assume all reactants are present in excess.

Question 12

Which type of reaction is characterized by the formation of a solid product from aqueous reactants?

Accepted Answer

Precipitation reaction

Question 13

If you have 5.00 moles of $$N_2$$ and 12.0 moles of $$H_2$$, how many moles of $$NH_3$$ can be produced according to $$N_2 + 3H_2$$ \rightarrow 2NH_3$$?

Accepted Answer

8.00 moles

Question 14

Which equation correctly relates moles of reactant A to moles of product B using stoichiometric coefficients?

Accepted Answer

$$	ext{Moles B} = \frac{n_B}{n_A} 	imes 	ext{Moles A}$$

Question 15

Which of the following is a combination reaction?

Accepted Answer

$$N_2 + 3H_2$$ \rightarrow 2NH_3$$

Question 16

Which statement about the law of conservation of mass is true in the context of chemical reactions?

Accepted Answer

The total mass of reactants equals the total mass of products in a balanced chemical equation.

Question 17

In the reaction $$C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$$, what is the ratio of moles of $$O_2$$ consumed to moles of $$CO_2$$ produced?

Accepted Answer

$$\frac{5}{3}$$

Question 18

A gas evolution reaction is characterized by which of the following?

Accepted Answer

Formation of bubbles due to a gaseous product.

Question 19

Which of the following is true about stoichiometric coefficients in a balanced chemical equation?

Accepted Answer

They represent the relative number of moles of each substance involved in the reaction.

Chapter 4: Chemical Reactions and Chemical Quantities – Study Notes

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