POST UTME UNN 2021 Chemistry | Objective
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Question 1
A 25.0 mL sample of 0.100 M HCl is titrated with 0.100 M NaOH. Calculate the pH of the solution after 10.0 mL of NaOH has been added.
Question 2
A 10 mL sample of a 0.1 M solution of NaOH is titrated with 0.1 M HCl. What is the pH of the solution after the titration?
Question 3
Determine the major product of the reaction between 2-methylpropene and HCl.
Question 4
The half-life of a radioactive subs\tance is 5 years. If the initial amount of the subs\tance is 100 g, what is the amount remaining after 10 years?
Question 5
A 2.0 M solution of HCl is mixed with a 1.0 M solution of NaOH in a 1:1 ratio. What is the pH of the resulting solution?
Question 6
At 25°C, the vapor pressure of a liquid is 755 mmHg. If the temperature is increased to 50°C, what is the new vapor pressure?
Question 7
A 2.50-g sample of a hydrocarbon is burned in a bomb calorimeter, relea\sing 12.1 kJ of heat energy. What is the molar mass of the hydrocarbon?
Question 8
The reaction of cyclohexane with bromine in the presence of light is an example of a(n) _______________________ reaction.
Question 9
The atomic radius of \( \text{Na} \) is \( 186 , \text{pm} \). If the atomic radius of \( \text{K} \) is \( 227 , \text{pm} \), calculate the percentage increase in atomic radius from \( \text{Na} \) to \( \text{K} \).
Question 10
A 2.5 M solution of HCl is mixed with a 1.5 M solution of NaOH. What is the concentration of the resulting solution?
Question 11
The half-reaction for the oxidation of \( \text{Zn} \) is \( \text{Zn} \rightarrow \text{Zn}^{2+} + 2e^- \). If \( 2.5 , \text{g} \) of \( \text{Zn} \) is oxidized, calculate the number of moles of electrons transferred.
Question 12
The van der Waals equation is given by \( left\( P + \frac{a}{V^2} \right \ \) \( V - b \) = RT ). If the gas cons\tant \( R = 0.0821 , \text{L atm} , \text{K}^{-1} , \text{mol}^{-1} \), the van der Waals cons\tant \( a = 2.17 , \text{L}^2 , \text{atm}^2 , \text{mol}^{-2} \), and the van der Waals cons\tant \( b = 4.17 \times 10^{-2} , \text{L} , \text{mol}^{-1} \), calculate the pressure ( P ) in atm when the volume \( V = 2.5 , \text{L} \) and the temperature \( T = 300 , \text{K} \).
Question 13
The pH of a solution is 4.5. What is the concentration of hydrogen ions in the solution?
Question 14
Calculate the s\tandard enthalpy change (ΔH°) for the reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s). Given that the s\tandard enthalpy of formation (ΔHf°) for Al2O3(s) is -1675.7 kJ/mol, and the s\tandard enthalpy of formation for Fe(s) is 0 kJ/mol.
Question 15
A 1.0 M solution of NaOH is mixed with a 2.0 M solution of HCl in a 1:2 ratio. What is the pH of the resulting solution?
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