| Date | May 2011 | Marks available | 1 | Reference code | 11M.1.sl.TZ1.22 |
| Level | SL | Paper | 1 | Time zone | TZ1 |
| Command term | Identify | Question number | 22 | Adapted from | N/A |
Question
Consider the equilibrium below.
\[{\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH(aq)}} + {{\text{H}}_{\text{2}}}{\text{O(l)}} \rightleftharpoons {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{CO}}{{\text{O}}^ - }{\text{(aq)}} + {{\text{H}}_{\text{3}}}{{\text{O}}^ + }{\text{(aq)}}\]
Which species represent a conjugate acid-base pair?
A. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH}}\) and \({{\text{H}}_{\text{2}}}{\text{O}}\)
B. \({{\text{H}}_{\text{2}}}{\text{O}}\) and \({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{CO}}{{\text{O}}^ - }\)
C. \({{\text{H}}_{\text{3}}}{{\text{O}}^ + }\) and \({{\text{H}}_{\text{2}}}{\text{O}}\)
D. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{CO}}{{\text{O}}^ - }\) and \({{\text{H}}_{\text{3}}}{{\text{O}}^ + }\)
Markscheme
C
