General Chemistry Answers

ulfur trioxide (SO3) is produced from the oxidation of SO2 as follows:

2 SO2 + O2 → 2 SO3

A 23-g sample of SO2 gives 18 g of SO3. Calculate the percent yield of sulfur trioxide, SO3.

A. 10 %

Automotive airbags inflate when sodium azide decomposes explosively to its constituent elements. How many moles of NA are produced by the decomposition of 1.75 mol of sodium azide

Sulfur trioxide decomposes at high temperature in a sealed container according to the reaction 2SO₃(g) ⇆ 2SO₂(g) + O₂(g)

Initially, the vessel is charged at 1000 K with SO₃(g) at a partial pressure of 0.500 atm. At equilibrium the SO₃ partial pressure is 0.200 atm. At equilibrium the SO₃ partial pressure is 0.200 atm. Calculate the value of Kp at 1000 K.

Strategy:

Using the equilibrium table, tabulate the given intial and equilibrium partial pressures. Denote the changes in partial pressure using a variable as guided by stoichiometric coefficients in the balanced chemical equation. Solve for the unknown to calculate for the equilibrium partial pressures of SO₂ and O₂ and then solve for Kp.

A mixture of 0.100 mol of NO, 0.050 mol of H₂ and 0.10 mol of H₂O is placed in a 1.0-L vessel at 300 K. The following equilibrium is established:

2NO(g) + 2H₂(g) ⇆ N₂(g) + 2H₂O(g).

At equilibrium [NO] = 0.062M. Calculate the equilibrium concentrations of H_2, N₂ and H₂O and Keq.

Strategy:

Using the balanced chemical equation, write the equilibrum constant expression, Kc, then substitute the given equilibrium concentrations to it.

A mixture of 0.100 mol of NO, 0.050 mol of H₂ and 0.10 mol of H₂O is placed in a 1.0-L vessel at 300 K. The following equilibrium is established:

2NO(g) + 2H₂(g) ⇆ N₂(g) + 2H₂O(g).

At equilibrium [NO] = 0.062M. Calculate the equilibrium concentrations of H_2, N₂ and H₂O and Keq.

Sulfur trioxide decomposes at high temperature in a sealed container according to the reaction 2SO₃(g) ⇆ 2SO₂(g) + O₂(g)

Initially, the vessel is charged at 1000 K with SO₃(g) at a partial pressure of 0.500 atm. At equilibrium the SO₃ partial pressure is 0.200 atm. Calculate the value of Kp at 1000 K.

Strategy:

Using the equilibrium table, tabulate the given initial and equilibrium partial pressures. Denote the changes in partial pressure using a variable as guided by stoichiometric coefficients in the balanced chemical equation. Solve for the unknown to calculate for the equilibrium partial pressures of SO₂ and O₂ and then solve for Kp.

An aqueous solution of acetic acid is found to have the following concentrations at 25°C: [CH₃COOH] = 1.65 x 10-2 M; [H30+] = 5.44 x 10^-4 M; and [CH₃COO-] = 5.44 x 10+ M. Calculate the equilibrium at 25°C. The reaction is:

CH₃COOH(aq) + H₂O(I) ⇆ H₃O(aq) + CH₃COO-(aq)

Strategy:

Using the balanced chemical equation, write the equilibrium constant expression, Kc, then substitute the given equilibrium concentrations to it.

An aqueous solution of acetic acid is found to have the following concentrations at 25°C: [CH₃COOH] = 1.65 x 10-2 M; [H30+] = 5.44 x 10^-4 M; and [CH₃COO-] = 5.44 x 10+ M. Calculate the equilibrium at 25°C. The reaction is:

CH₃COOH(aq) + H₂O(I) ⇆ H₃O(aq) + CH₃COO-(aq)

How is Gibbs free energy change determined when ΔH and ΔS are available?

ΔG = ΔH - TΔS

Ozone (O₃) in the atmosphere can react with nitric oxide (NO):

O_3(g) + NO_(g) > NO_2(g) + O_2(g)

Calculate the G for this reaction at 25°C.

(H = -199 kJ/mol, S = -4.1 J/K•mol)

Determine S for the reaction:

SO_3(g) + H₂O_(I) > H₂SO_4(I)

Given: S° (J/K•mol): 256.2 69.9 156.9