POST UTME WELLSPRING UNIVERSITY 2019 Chemistry | Objective

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Question 1
The s\tandard Gibbs free energy change \( ΔG^circ \) for the reaction: 2Al(s) + 6HCl(aq) → 2AlCl_3(aq) + 3H_2(g) is -1072.1 kJ/mol. Calculate the equilibrium cons\tant (K) for the reaction.
A. 1.00 × 10^\( -3 \)
B. 1.00 × 10^\( -6 \)
C. 1.00 × 10^\( -9 \)
D. 1.00 × 10^\( -12 \)
Question 2
Calculate the s\tandard enthalpy change (ΔH°) for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). The s\tandard enthalpy of formation (ΔHf°) for Al2O3(s) is -1675.7 kJ/mol, and for Fe2O3(s) is -826.4 kJ/mol. The s\tandard enthalpy of formation for Al(s) is 0 kJ/mol, and for Fe(s) is 0 kJ/mol. Assume the reaction occurs at 298 K.
A. -1821.1 kJ/mol
B. -1821.5 kJ/mol
C. -1821.9 kJ/mol
D. -1822.3 kJ/mol
Question 3
A 2.0 M solution of NaOH is prepared by dissolving 2.0 g of NaOH in 100 mL of water. What is the concentration of NaOH in the solution?
A. 0.05 M
B. 0.1 M
C. 0.2 M
D. 0.4 M
Question 4
A 1 M solution of NaOH is prepared by dissolving 40 g of NaOH in 1000 mL of water. What is the concentration of the solution in mol/L?
A. 0.1 M
B. 0.5 M
C. 1 M
D. 2 M
Question 5
A diagram of a titration setup is shown below. Identify the part labeled A.
A. Burette
B. Beaker
C. Conical Flask
D. Test Tube
Question 6
The half-life of a radioactive subs\tance is 3 years. If the initial activity is 500 Bq, what is the activity after 9 years?
A. 125 Bq
B. 250 Bq
C. 500 Bq
D. 1000 Bq
Question 7
Determine the pH of a 0.1 M solution of HCl.
A. 1
B. 2
C. 3
D. 4
Question 8
The s\tandard enthalpy change \( ΔH^circ \) for the reaction: 2Al(s) + 6HCl(aq) → 2AlCl_3(aq) + 3H_2(g) is -572.4 kJ/mol. Calculate the s\tandard entropy change \( ΔS^circ \) for the reaction.
A. -192.3 J/K
B. -192.4 J/K
C. -192.5 J/K
D. -192.6 J/K
Question 9
The rate cons\tant (k) of a first-order reaction is 0.05 min^-1. If the initial concentration of the reac\tant is 0.1 M, what is the concentration of the reac\tant after 10 minutes?
A. 0.019 M
B. 0.039 M
C. 0.049 M
D. 0.059 M
Question 10
A 1 M solution of HCl is prepared by dissolving 36.5 g of HCl in 1000 mL of water. What is the concentration of the solution in mol/L?
A. 0.1 M
B. 0.5 M
C. 1 M
D. 2 M
Question 11
A 2.5 g sample of a polymer is dissolved in 50 mL of a solvent. The solution is then diluted to 100 mL. What is the concentration of the polymer solution in g/L?
A. 0.05 g/L
B. 0.1 g/L
C. 0.5 g/L
D. 1 g/L
Question 12
A 1 M solution of HCl is prepared by dissolving 36.5 g of HCl in 1000 mL of water. What is the concentration of the solution in mol/L?
A. 0.1 M
B. 0.5 M
C. 1 M
D. 2 M
Question 13
A 1.0 M solution of HCl is prepared by dissolving 1.0 g of HCl in 100 mL of water. What is the concentration of HCl in the solution?
A. 0.0274 M
B. 0.0548 M
C. 0.1096 M
D. 0.218 M
Question 14
A 0.500 M solution of NaOH is prepared by dissolving 25.0 g of NaOH in 1.00 L of water. Calculate the pH of the solution.
A. 12.3
B. 13.3
C. 14.3
D. 15.3
Question 15
A 3.0 M solution of NaOH is prepared by dissolving 3.0 g of NaOH in 100 mL of water. What is the concentration of NaOH in the solution?
A. 0.075 M
B. 0.15 M
C. 0.3 M
D. 0.6 M

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