CHEM 104 Final Exam ; Questions and Answers 100% Solved A buffer solution contains acetic acid (HC2H3O2) at a concentration of 0.225 M and sodium acetate (NaC2H3O2) at a concentration of 0.164 M. The value of Ka for acetic acid is 1.75 × 10−5. What is the pH of this buffer solution? Correct answer -4.62 Consider two beakers, one containing 1.0 M HCl and the other containing 1.0 M CH3COOH. Which solution would have the lowest pH? Correct answer -1.0 M HCl because its solution contains a higher hydronium ion concentration than 1.0 M CH3COOH Which of the following correctly describes what is meant by the term neutralization? Correct answer -the reaction between an acid and a base to form a salt and water Consider the following generalized buffer solution equilibrium: BH+(aq) + H2O(l) H3O+(aq) + B(aq) When a small amount of a strong base such as sodium hydroxide is added to the solution, which of the four species shown would experience an increase in concentration? (Hint: Use LeChatelier's principle.) Correct answer -B Which statement concerning the relative strength of acids is FALSE? Correct answer -
Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases. What is the pH of a 0.035 M HCl solution? Correct answer -1.46 A buffer solution is prepared by placing twice the concentration of propanoic acid (C2H5COOH, Ka=1.34 ×10−5) as the concentration of its conjugate base sodium propanoate into a flask. The pH of the resulting buffer solution is best described as which of th e following? Correct answer -less than 4.87 The species that remains after an acid donates a proton is called its conjugate base. What is the conjugate base of the hydronium ion, H3O+? Correct answer -H2O CHEM 104 Final Exam ; Questions and Answers 100% Solved Which one of the following is NOT a characteristic property of a base? Correct answer -
increases [H+] in water What is the conjugate acid of NH2−? Correct answer -NH3 Butyric acid is a weak acid. Which reaction equation properly represents the dissociation of butyric acid in water? Correct answer -H3CH2CH2COOH(aq) + H2O(l) = CH3CH2CH2COO -(aq) + H3O+(aq) Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O+] = 1.1 × 10−10 M, what is the pH of this solution? Correct answer -9.96 What is always a characteristic of a solution that contains a buffer? Correct answer -The solution resists large changes in pH when small amounts of acids or bases are added. The reaction of an acid with a base produces a salt and another product. What is the identity of the other product Correct answer -water A buffer solution contains carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3), each at a concentration of 0.100 M. The relevant equilibrium is shown below. What is the pH of this buffer solution? H2CO3(aq) + H2O(l) === H3O+(aq) + HCO3−(aq) Ka = 4.5 × 10−7 Correct answer -6.35 Which statement correctly describes conjugate acids and bases according to the Brønsted -
Lowry theory? Correct answer -A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton. If the hydronium ion concentration of an aqueous solution at 25°C is 5 × 10−6 M, what is the hydroxide ion concentration? Correct answer -: 2 × 10^−9 M
Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases. What is the pH of a 0.035 M HCl solution? Correct answer -1.46 A buffer solution is prepared by placing twice the concentration of propanoic acid (C2H5COOH, Ka=1.34 ×10−5) as the concentration of its conjugate base sodium propanoate into a flask. The pH of the resulting buffer solution is best described as which of th e following? Correct answer -less than 4.87 The species that remains after an acid donates a proton is called its conjugate base. What is the conjugate base of the hydronium ion, H3O+? Correct answer -H2O CHEM 104 Final Exam ; Questions and Answers 100% Solved Which one of the following is NOT a characteristic property of a base? Correct answer -
increases [H+] in water What is the conjugate acid of NH2−? Correct answer -NH3 Butyric acid is a weak acid. Which reaction equation properly represents the dissociation of butyric acid in water? Correct answer -H3CH2CH2COOH(aq) + H2O(l) = CH3CH2CH2COO -(aq) + H3O+(aq) Morphine is used medicinally as a pain reliever. If an aqueous solution of morphine has [H3O+] = 1.1 × 10−10 M, what is the pH of this solution? Correct answer -9.96 What is always a characteristic of a solution that contains a buffer? Correct answer -The solution resists large changes in pH when small amounts of acids or bases are added. The reaction of an acid with a base produces a salt and another product. What is the identity of the other product Correct answer -water A buffer solution contains carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3), each at a concentration of 0.100 M. The relevant equilibrium is shown below. What is the pH of this buffer solution? H2CO3(aq) + H2O(l) === H3O+(aq) + HCO3−(aq) Ka = 4.5 × 10−7 Correct answer -6.35 Which statement correctly describes conjugate acids and bases according to the Brønsted -
Lowry theory? Correct answer -A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton. If the hydronium ion concentration of an aqueous solution at 25°C is 5 × 10−6 M, what is the hydroxide ion concentration? Correct answer -: 2 × 10^−9 M
