Gibbs Free Energy, Equilibrium in Reactions

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The following three questions refer to the material you were to read in preparation for the lesson. Questions one and two require you to write a three or four sentence response. Number three is a multiple choice question. Click in the appropriate circle.

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1.

The Law of Mass Action says that the product of the concentrations of the reactants (n_j), each raised to a power which is the coefficient of that species in the chemical reaction (j), is a function of the temperature alone. That is, the product of n_j^j multiplied for all species j is equal to K().

In your own words, explain why you think K is a function of just the temperature.

Would K() be the same value for the reactions

H₂O H₂ + 1/2 O₂
and
2H₂O 2H₂ + O₂?

Why or why not? (Note: The reactions are the same, but have different coefficients.)

2.

The chemical reaction that describes the burning of parafin is:

2 C₂₀H₄₂ + 61 O₂ 40 CO₂ + 42 H₂O.

What would be an equation that would describe the equilibrium condition for this chemical reaction?

3.

Pure water has a pH of 7. (Recall, pH = -log₁₀[H⁺].) In something that is acidic enough that its pH level is 3, what is the approximate equilibrium concentration of OH^- ions?

[OH^-] = 10^-14 mol²/liter²
[OH^-] = 10^-3 mol²/liter²
[OH^-] = 10^-11 mol²/liter²
Not enough information is provided to determine the answer.

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