Reversible Reactions Quiz: Examples and Equilibrium

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Questions and Answers

Describe reversible reactions such as the dehydration of hydrated copper(II) sulfate and the effect of heat on ammonium chloride.

Reversible reactions are reactions that can proceed in both forward and reverse directions. The dehydration of hydrated copper(II) sulfate involves the removal of water molecules from the copper(II) sulfate crystals. When heated, ammonium chloride decomposes into ammonia gas and hydrogen chloride gas. These reactions are reversible because by applying the appropriate conditions (e.g., adding water or cooling the mixture) you can reverse the process and reform hydrated copper(II) sulfate or ammonium chloride.

Some reactions are reversible and this is indicated by the symbol '⇌' in equations.

True (A)

Describe a test for the presence of water using anhydrous copper(II) sulfate.

Anhydrous copper(II) sulfate is a white powder that turns blue in the presence of water. This is because the copper(II) sulfate absorbs water molecules to form hydrated copper(II) sulfate, which is blue. To test for the presence of water, you can add a small amount of anhydrous copper(II) sulfate to the sample. If the powder turns blue, then water is present.

Describe a physical test to show whether a sample of water is pure.

A simple way to determine if a sample of water is pure is by measuring its boiling point using a thermometer. Pure water has a specific boiling point of 100 °C (212 °F) at standard atmospheric pressure. Any impurities, like dissolved salts or other substances, will affect the boiling point of the water. If the boiling point deviates from 100°C, it is an indication that the water sample is not pure. Signup and view all the answers

A reversible reaction can reach dynamic equilibrium in a sealed container.

True (A) Signup and view all the answers

What are the characteristics of a reaction at dynamic equilibrium? (Select all that apply)

The concentrations of reactants and products remain constant. (B), The forward and reverse reactions occur at the same rate. (D) Signup and view all the answers

Explain the effect of changing either temperature or pressure on the position of equilibrium in a reversible reaction.

Changes in temperature or pressure can affect the position of equilibrium in a reversible reaction. Increasing temperature favors the endothermic reaction. Increasing pressure favors the reaction that produces fewer moles of gas. Conversely, decreasing temperature favors the exothermic reaction, while decreasing pressure favors the reaction that generates more moles of gas. The position of equilibrium shifts to counter these changes. Signup and view all the answers

References to Le Chatelier's principle are not required to understand why a catalyst does not affect the position of equilibrium in a reversible reaction.

True (A) Signup and view all the answers

What occurs when a reversible reaction reaches dynamic equilibrium?

The rates of the forward and reverse reactions become equal. (B) Signup and view all the answers

How does an increase in temperature affect a reversible reaction at equilibrium?

It shifts the equilibrium in the direction of the endothermic reaction. (C) Signup and view all the answers

Which statement accurately describes a characteristic of a catalyst in a reversible reaction?

It accelerates both the forward and reverse reactions equally. (B) Signup and view all the answers

What effect does an increase in pressure have on a reversible reaction that produces fewer moles of gas?

It shifts the equilibrium towards the side with fewer moles of gas. (B) Signup and view all the answers

Which of the following statements regarding dynamic equilibrium is incorrect?

The reaction has stopped completely. (D) Signup and view all the answers

Flashcards

Reversible reaction

A reaction that can proceed in both forward and reverse directions.

Dynamic equilibrium

A state where the forward and reverse reactions occur at the same rate, and the concentrations of reactants and products remain constant.