Can you please explain and answer question 5? Thank you! :) AP Test Equilibrium-
ID: 570357 • Letter: C
Question
Can you please explain and answer question 5?Thank you! :) AP Test Equilibrium-Unit 13 Date Multiple Choice Questions 1 and 2 refer to the following information: 1. Which acid solution has a greater pH? A) HA because it dissociates less than HX (B) HA because it dissociates more than HX (C) HX because it dissociates less than HA (D) HX because it dissociates more than HA 2. How would diluting HA from 0.15 M to 0.005 M affect the pH of the solution? (A) The pH would decrease because the [H'1 decreases (B) The pH would decrease because the l increases. 9 The pH would increase because the [H') decreases. (D) The pH would increase because the [f' increase In a research project, a scientist adds 0.1 mole of HCN·0.1 mole of H ,and 0.1 mole of ar to water to make a total volume of 1 L Will this reaction proceed to a greater extent in the forward direction or in the reverse direction? 3. A) Forward; acids always dissociate in water. ) Forward; the K value is less than 1. Reverse; the K value is less than 1 (D) Reverse; water cannot be a reactant 4. What is the conjugate acid of HPO A) HiO (B) PO C) HPO (D) HiPO is a chemical indicator that turns blue at pH values greater than 7. in which of these color be observed if 2 drops of bromothymoll blue were of each solution is 0.10 M. K. for HCHOlaq) A) NH C 1.8 x 10-s., for NHlaq) 1.8x10-s. =
Explanation / Answer
Multiple choice
5. Bromothymol blue gives blue color in solutions with pH greater than 7.
If two drops of bromothymol blue is added, the solution which would show blue color is,
(D) NaC2H3O2
C2H3O2- is a conjugate base of weak acid HC2H3O2 which hydrolyzes in solution to form OH- ions, which gives it pH value greater than 7.
NaC2H3O2 --> Na+ + C2H3O2-
C2H3O2- + H2O <==> HC2H3O2 + OH- (base)