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Chemical Equilibrium

1. Define dynamic equilibrium state in terms of
a) reaction rates
b) change in observable properties
c) energy and entropy state

2. In which of these closed containers is the vapour pressure the greatest? Explain the choice.
a) a 1 L container with 5 mL of water held at 20˚C
b) a 1 L container with 15 mL of water held at 30˚C
c) a 1 L container with 500 mL of water held at 25˚C

3. At the top of a mountain, an egg is heated in boiling water for four minutes and is foun to be uncooked. Explain.

4. Ethanol and water are completely miscible; that is, they dissolve in each other in all propoartions.
a) When the two substances are mixed, is randomness increased or decreased?
b) Heat is liberated in the dissolving process. Does the tendency toward minimum energy favour the separated pure substances, or the solution of one in the other?
c) In view of the tendencies listed in (a) and (b) above, explain why water and ethanol are completely miscible.

Solution Preview

1. Define dynamic equilibrium state in terms of

a) reaction rates

b) change in observable properties

c) energy and entropy state

Answer - Dynamic equilibrium occurs when the rate at which a chemical substance reacts is equal to the rate at which it is formed. Reaction rates are equal in a dynamic equilibrium state. The concentration of reactants and products remain constant over time due to forward and reverse reactions occurring simultaneously. Two opposing processes are going on at an equal rate and the system undergoes no observable changes. Energy and entropy states are in competition with each other. When a system is in equilibrium the two opposing drives are said to ...

Solution Summary

Problems and solutions illustrating chemical equilibrium.

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