POST UTME REDEEMERS UNIVERSITY 2020 Chemistry | Objective
Practice these randomly selected questions to test your readiness.
Question 1
A solution containing 0.05 M H2SO4 is titrated with 0.05 M NaOH. What is the pH of the solution after the addition of 20 mL of NaOH?
Question 2
The s\tandard enthalpy change \( ΔH^circ \) for the reaction: C(s) + O2(g) → CO2(g) is -393.5 kJ/mol. Calculate the s\tandard entropy change \( ΔS^circ \) for the reaction, given that the s\tandard entropy of C(s) is 5.7 J/mol*K, the s\tandard entropy of O2(g) is 205.1 J/mol*K, and the s\tandard entropy of CO2(g) is 213.8 J/mol*K.
Question 3
The s\tandard Gibbs free energy change \( ΔG^circ \) for the reaction: 2AgCl(s) → 2Ag(s) + Cl2(g) is 67.3 kJ/mol. Calculate the equilibrium cons\tant (K) for the reaction.
Question 4
A diagram of a simple distillation setup is shown below. If the boiling point of the mixture is 90°C, and the \fraction of the mixture that is water is 0.3, what is the boiling point of the mixture?
Question 5
A polymer has a molecular weight of 50,000 g/mol and a degree of polymerization of 500. Calculate the molar mass of the repeating unit.
Question 6
The pH of a solution is 4.5. What is the concentration of hydrogen ions in the solution?
Question 7
A 2.5 L flask contains 0.5 mol of an ideal gas at a temperature of 300 K. What is the pressure of the gas?
Question 8
A sample of 2.0 g of an unknown compound \( C_xH_yO_z \) is dissolved in 100 mL of water, and the resulting solution is titrated with 0.1 M HCl. If 25 mL of HCl is required to neutralize the solution, what is the empirical formula of the compound?
Question 9
A 1.0 M solution of HCl is titrated with a 1.0 M solution of NaOH. If 20 mL of the NaOH solution is required to reach the equivalence point, calculate the pH of the solution at the equivalence point.
Question 10
A solution contains 0.1 M HCl and 0.2 M NaOH. Calculate the pH of the solution.
Question 11
A sample of oxygen gas is collected over water at a temperature of 25°C and a pressure of 1 atm. If the partial pressure of water vapor is 0.031 atm, what is the partial pressure of oxygen gas?
Question 12
A sample of a non-metal has a mass of 2.5 g. If the density of the non-metal is 5.6 g/cm^3, what is the volume of the sample?
Question 13
A 2.0 M solution of HCl is titrated with a 2.0 M solution of NaOH. If 15 mL of the NaOH solution is required to reach the equivalence point, calculate the number of moles of HCl present in 50 mL of the HCl solution.
Question 14
A 1.00 L sample of a gas at 25°C and 1.00 atm is compressed to 2.00 atm. Calculate the new volume of the gas.
Question 15
A metal (X) reacts with chlorine gas to form a white solid. The reaction is as follows: 2X + Cl2 → 2XCl. If 2.5 g of X reacts with 1.5 g of Cl2, what is the mass of XCl formed?
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