CHEM 1212: Final Exam Questions and Answers

CHEM 1212: Final Exam Questions and Answers Colligative Properties - CORRECT ANSWER-properties of solution, such as freezing point and boiling point, which depend on the concentration of solute particles dissolved in the solvent Freezing Point Depression Equation - CORRECT ANSWERMolality - CORRECT ANSWER-moles of solute per kg of solvent Molality= - CORRECT ANSWERWhat is the definition of colligative properties? (Antifreeze) - CORRECT ANSWERproperties of a solution that depend on the concentration of solute dissolved in the solvent What is the difference between solute and solvent? (Antifreeze) - CORRECT ANSWERThe solute is what is dissolved, and the solvent is what is doing the dissolving. What is the difference between molality and molarity? (Antifreeze) - CORRECT ANSWER-molality=mol/kg molarity=mol/L What is the difference between freezing point and melting point? (Antifreeze) - CORRECT ANSWER-There is no difference between the melting point and boiling point. The freezing point and boiling point depends on the direction of the reaction -- whether a solid or liquid is being formed. An antifreeze solution contains 25 mL of ethylene glycol and 75 mL of water. What is the molality of the solution? (density of H2O = 1.00 g/mL and density of C2H4(OH)2 = 1.11 g/mL) (Antifreeze) - CORRECT ANSWER-5.96 m What will be the freezing point of the antifreeze solution in the question above? (Antifreeze) V of C2H4(OH)2 (mL): 25 mL V of H2O (mL): 75 mL Density of H2O (g/mL): 1.00 g/mL Density of C2H4(OH)2 (g/mL): 1.11 g/mL Kf of H2O: 1.86 *C/m Tf of H2O: 0 *C - CORRECT ANSWER--11.09 *C A different antifreeze solution contains 45 mL of ethylene glycol and 55 mL of water. What will be the freezing point of this new solution? (Antifreeze) Density of H2O (g/mL): 1.00 g/mL Density of C2H4(OH)2 (g/mL): 1.11 g/mL Kf of H2O: 1.86 *C/m Tf of H2O: 0 *C - CORRECT ANSWER--27 *C Based on your results, which of the following antifreeze solutions will be the best at protecting your radiator from freezing? (Antifreeze) A. 100% water B. 2 m ethylene glycol C. 12 m ethylene glycol D. pure ethylene glycol - CORRECT ANSWER-C. 12 m ethylene glycol Some students mislabeled their test tubes. The test tube really contained 2.5 mL of ethylene glycol instead of 2.0 mL. Will this affect the observed experimental melting point? If so, will this melting point be higher or lower than expected? Explain your answer. (Antifreeze) - CORRECT ANSWER-If the test tube contained 2.5 mL of ethylene glycol instead of 2.0 mL, the melting point will be lower than expected because the more concentrated the ethylene glycol solution is, the lower the melting point of the solution. Regular thermometers are filled with mercury. Mercury freezes at -39 *C. Can regular thermometers be used for this experiment? Explain your answer. (Antifreeze) - CORRECT ANSWER-Regular thermometers could not be used for this experiment because the ethylene glycol solutions reached temperatures lower than mercury's freezing point, which would mark the thermometer as ineffective. Another colligative property of solutions is boiling point. As the concentration of particles in the solution increases, the boiling point increases. Which of your antifreeze mixtures would be best for keeping your radiator from overheating? (Antifreeze) - CORRECT ANSWER-The most concentrated ethylene glycol solution would be best for keeping the radiator from overheating. A new antifreeze solution contains 65 mL of ethylene glycol and 35 mL of water. What will be the boiling point of this new solution? (Antifreeze) Density of H2O (g/mL): 1.00 g/mL Density of C2H4(OH)2 (g/mL): 1.11 g/mL Kb of H2O: 0.52 *C/m Tb of H2O: 100 *C - CORRECT ANSWER-117 *C Acid - CORRECT ANSWER-any substance that donates a proto