SAT Subject Test Chemistry,10 edition

6 . Identify    the conjugate   acids   and bases   in  the following   equation:

NH 3 + H 2 O NH 4 + + OH−

7 . Identify    each    of  the following   as  an  Arrhenius   acid    or  base,   Brønsted-Lowry  acid    or  base,

or  Lewis   acid    or  base:

(A) NaOH,   in  NaOH    →   Na+ +   OH−

(B) HCl,    in  HCl →   H+  +   Cl−

(C) NH 3 ,  in  NH 3    +   H+  →   NH 4 +

(D) NH 4 +, in  NH 4 +  →   NH 3    +   H+

(E) (CH 3 ) 3 N:,   in  (CH 3 ) 3 N:    +   BF 3    →   (CH 3 ) 3 N:BF 3

8 . At  equilibrium,    a   certain acid,   HA, in  solution    yields  [HA]    =   0.94    M   and [A−]    =   0.060   M.

(A) Calculate   Ka.

(B) Is  this    acid    stronger    or  weaker  than    sulfurous   acid    (Ka =   1.7 ×   10−2)?

(C) Calculate   Kb.

(D) Calculate   pH.

9 . For each    of  the following   choices,    choose  that    which   describes   the weaker  acid:

(A) Ka  =   X,  Ka  =   3X

(B) [H+]    =   X,  [H+]    =   3X

(C) pH  =   X,  pH  =   3X

10 . For a certain acid, HA, Kb(A−) = 2.22 × 10−11. Calculate the pH of a 0.5 M solution of HA.

11 . Which of the following sets of materials would make the best buffer solution?