(c) What is the formula of the solid product?

(d) Write a balanced equation for the reaction. Assume that the empirical formula of the

gas is the true formula.

3. Methyl alcohol oxidizes to produce methanoic (formic) acid and water according to the
   following reaction and structural diagram:
   CH 3 OH(aq) + O 2 (g) →HCOOH(aq) + H 2 O(l)

Given the following data:

Substance ∆H%f(kJ/mole) S°(J/K ⋅mole)

CH 3 OH(aq) −238.6 129

O 2 (g) 0 205.0

HCOOH(aq) −4 0 9 12 7. 0

H 2 O(l) −285.84 69.94

(a) Calculate ∆H°for the oxidation of methyl alcohol.

(b) Calculate ∆S°for the oxidation of methyl alcohol.

(c) (1) Is the reaction spontaneous at 25°C? Explain.

(2) If the temperature were increased to 100°C, would the reaction be spontaneous?

Explain.

(d) The heat of fusion of methanoic acid is 12.7 kJ/mole, and its freezing point is 8.3°C.

Calculate ∆S°for the reaction

HCOOH(l) →HCOOH(s)

(e) (1) What is the standard molar entropy of HCOOH(s)?

S°HCOOH(l) = 109.1 J/mole ⋅K.

(2) Is the magnitude of S°for HCOOH(s) in agreement with the magnitude of S°for

HCOOH(l)? Explain.

(f) Calculate ∆G°for the ionization of methanoic acid at 25°C. Ka= 1.9 × 10 –4.

+

H

CO

H

H H O 2 H COH+H 2 O

O

Practice Test

Section

II

Free-Response Questions

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