CEM 142 MOCK EXAM 2 QUESTIONS AND ANSWERS ALREADY PASSED

CEM 142 MOCK EXAM 2 QUESTIONS AND ANSWERS ALREADY PASSED Imagine a reaction in which compound A (which is a blue compound) reacts with compound B (which is a yellow compound) to give AB. A2 + B2 -- 2AB What can you say about the color of compound AB? It is impossible to predict what the color of AB is from the information given Which acid is the strongest of CH4 NH3 OH2 and HF HF because H and F are small atoms - more bond overlap, not willing to share electrons, most positive charge on proton, most electronegative Which is the strongest base of -CH3 -NH2 -OH and F- Why? -CH3 it's the least stable and most reactive. The negative charge on the carbon is not very electronegative. C has the lowest effective nuclear charge, and is the least able to stabilize the extra negative charge by interactions with the positive charge on the nucleus, willing to share electrons. CH4 (the conjugate acid) is the weakest acid When a bond forms between two atoms.. energy is released to the surroundings Which is a stronger acid, NH3 or H2O? H2O, because O is more electronegative than N, and therefore is better able to stabilize the charge on the conjugate base When this reaction occurs: H2O + NH3 -- -OH + NH4+ Do you think the final reaction mixture contains: More reactants than products because H2O + NH3 are weaker acids and bases than -OH + NH4+ What is the pH of a 0.10 M solution of HNO3 at 25°C? -log (0.1)= 1.0 What is the pH of a 0.10 M solution of KOH at 25°C? -log (1 x 10^-14/ 0.1) = 13.0 If the pH of a 0.020 M acid is 1.70 what does that tell you about the acid? I. The acid is completely ionized. II. The acid is strong. III. The acid is not completely ionized. IV. The acid is weak. I, II What is the percent ionization in a 0.10 M solution of an acid that has a pH of 3.75? find [H30+]: =10^-3.75= 0.000178 find % ionization: 0.000178/0.01 x100= 0.178 % What is the oxidation number of C in H2CO3? +4 In the reaction Zn + Cu^2 -- Cu + Zn^2+ The zinc.. is oxidized in the reaction