Q: Which of the following is the correct definition of a mole (mol)?

A quantity equal to $$6.022 \times 10$$^{23}$$ particles (atoms or molecules).

Q: Which equation correctly relates enthalpy change ($$\Delta H) to $$the enthalpy of products and reactants?

$$\Delta H = H_{\text{products}} - H_{\text{reactants}}$$

Question 1

Which statement best describes the law of conservation of matter as it applies to chemical reactions?

Accepted Answer

The total number of atoms of each element is the same before and after a reaction.

Question 2

Given the reaction: $$2 \mathrm{H}_2 (g) + \mathrm{O}_2 (g) \rightarrow 2 \mathrm{H}_2\mathrm{O} (l)$$, how many moles of $$\mathrm{O}_2$$ are required to completely react with 10 moles of $$\mathrm{H}_2$$?

Accepted Answer

5 moles

Question 3

Which of the following is the correct definition of a mole (mol)?

Accepted Answer

A quantity equal to $$6.022 	imes 10$$^{23}$$ particles (atoms or molecules).

Question 4

Which of the following best describes what happens in an oxidation-reduction (redox) reaction?

Accepted Answer

Electrons are transferred from one atom to another.

Question 5

In the combustion of methane: $$\mathrm{CH}_4 (g) + 2 \mathrm{O}_2 (g) \rightarrow \mathrm{CO}_2 (g) + 2 \mathrm{H}_2\mathrm{O} (l)$$, what is oxidized and what is reduced?

Accepted Answer

Methane is oxidized; oxygen is reduced.

Question 6

What is the oxidation number of carbon in $$\mathrm{CO}_2$$?

Accepted Answer

$$+4$$

Question 7

Which of the following processes is exothermic?

Accepted Answer

Combustion of glucose in the body to produce energy.

Question 8

Which equation correctly relates enthalpy change ($$\Delta H) to $$the enthalpy of products and reactants?

Accepted Answer

$$\Delta H = H_{	ext{products}} - H_{	ext{reactants}}$$

Question 9

Which of the following statements about entropy ($$\Delta S) is $$correct?

Accepted Answer

Entropy is a measure of disorder in a system.

Question 10

Which process below represents an increase in entropy ($$\Delta S \u003e 0$$)?

Accepted Answer

Dissolving salt in water.

Question 11

Which equation correctly relates free energy change ($$\Delta G$$), enthalpy change ($$\Delta H$$), temperature ($$T$$), and entropy change ($$\Delta S$$)?

Accepted Answer

$$\Delta G = \Delta H - T\Delta S$$

Question 12

A reaction has $$\Delta H  0. $$What can you conclude about its spontaneity?

Accepted Answer

It is always spontaneous.

Question 13

Which of the following will NOT affect the equilibrium constant ($$K_{eq}) $$for a chemical reaction?

Accepted Answer

Adding a catalyst.

Question 14

For the reaction $$2 \mathrm{Na} (s) + 2 \mathrm{H}_2\mathrm{O} (l) ightleftharpoons \mathrm{H}_2 (g) + 2 \mathrm{NaOH} (aq) + 	ext{heat}$$, what happens to the position of equilibrium if you add heat?

Accepted Answer

It shifts to the left (reverse reaction).

Question 15

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy and increases the reaction rate.

Question 16

Which of the following statements about equilibrium is correct?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal.

Question 17

A reaction is endergonic if:

Accepted Answer

$$\Delta G is $$positive.

Question 18

Which of the following changes will shift the equilibrium position to the right for the reaction $$A + B \rightleftharpoons C + D$$?

Accepted Answer

Removing product D.

Question 19

Which of the following is a correct statement about catabolic and anabolic pathways in metabolism?

Accepted Answer

Catabolic pathways release free energy, while anabolic pathways require free energy.

Question 20

Which of the following will increase the rate of a chemical reaction?

Accepted Answer

Adding a catalyst.

Chemical Reactions: Stoichiometry, Redox, Thermodynamics, Kinetics, and Equilibrium

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