General Chemistry Questions & Answers

General Chemistry Questions & Answers A 25.0 mL solution of 0.2 M acetic acid (pKa = 4.76) is mixed with 50 mL of 1.0 M sodium acetate (pKb = 9.24). What is the final pH? A) 4.8 B) 5.8 C) 9.2 D) 10.2 - CORRECT ANSWER - B (CHEM257) A 36 gram sample of water requires 93.4 kJ to sublime. What are the heats of fusion (ΔHfus) and vaporization (ΔHvap) for water? A) ΔHfus = -20 kJ/mol, ΔHvap = 66.7 kJ/mol B) ΔHfus = 40.7 kJ/mol, ΔHvap = 6 kJ/mol C) ΔHfus = 6.0 kJ/mol, ΔHvap = 40.7 kJ/mol D) ΔHfus = 12.0 kJ/mol, ΔHvap = 81.4 kJ/mol - CORRECT ANSWER - C (CHEM137) A 6-litre container holds H2 (g) at a temperature of 400 K and a pressure of 3 atm. If the temperature is increased to 600 K, what will be the pressure? - CORRECT ANSWER - 4.5 atm (CHEM166) A balloon holds a mixture of fluorine, F2 (g), and helium, He (g). If the rms speed of the helium atoms is 540 m/s, what is the rms speed of the fluorine molecules? - CORRECT ANSWER - 180 m/s (CHEM174) A certain radioactive isotope is administered orally as a diagnostic tool to study pancreatic function and intestinal fat absorption. This radioisotope is known to undergo β- decay, and the daughter nucleus is xenon-131. What is the parent radioisotope? A) 131 Cs B) 131 I C) 132 I D) 132 Xe - CORRECT ANSWER - B (CHEM57) A certain reversible reaction comes to equilibrium with high concentration of products and low concentration of reactant. Of the following, which is the most likely value of the equilibrium constant for this reaction? A) Kep = -1 x 10^-5 B) Keq = 1 x 10^-5 C) Keq = 1 D) Keq = 1 x 10^5 - CORRECT ANSWER - D (CHEM204) A container holds methane (CH3) and sulfur dioxide (SO2) at a temperature of 227°C. Let KEm denote the average kinetic energy of the methane molecules and KEs the average kinetic energy of the sulfur dioxide molecules. Which of the following best describes the relationship between these energies? A) KEs = 4 KEm B) KEs = 3 KEm C) KEm = KEs D) KEm = 4 KEs - CORRECT ANSWER - C (CHEM175) A container holds methane (CH4) and sulfur dioxide (SO2), at a temperature of 227°C. Let vM denote the rms speed of the methane molecules and vS the rms speed of the sulfur dioxide molecules. Which of the following describes the relationship between these speeds? A) vS = 16 vM B) vS = 2 vM C) vM = 2 vS D) vM = 16 vS - CORRECT ANSWER - C (CHEM174) A fifty mL solution of HCOOH (formic acid) is titrated with 0.2 M NaOH. The equivalence point is reached when 40 mL of the NaOH solution has been added. What was the original concentration of the formic acid solution? - CORRECT ANSWER - 0.16 M (CHEM254) A gas is observed to undergo condensation. Which of the following is true about the process? A) ΔH is positive, and ΔS is positive B) ΔH is positive, and ΔS is negative C) ΔH is negative, and ΔS is positive D) ΔH is negative, and ΔS is negative - CORRECT ANSWER - D (CHEM131)