| Date | May 2015 | Marks available | 1 | Reference code | 15M.1.hl.TZ2.27 |
| Level | HL | Paper | 1 | Time zone | TZ2 |
| Command term | Question number | 27 | Adapted from | N/A |
Question
The \({\text{p}}{K_{\text{a}}}\) of ethanoic acid is 4.8 at 298 K. Which combination will produce a buffer solution with a pH of 4.8 at 298 K?
A. \({\text{20.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ C}}{{\text{H}}_{\text{3}}}{\text{COOH and 10.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ NaOH}}\)
B. \({\text{20.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ C}}{{\text{H}}_{\text{3}}}{\text{COOH and 20.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ NaOH}}\)
C. \({\text{10.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ C}}{{\text{H}}_{\text{3}}}{\text{COOH and 20.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ NaOH}}\)
D. \({\text{14.8 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ C}}{{\text{H}}_{\text{3}}}{\text{COOH and 10.0 c}}{{\text{m}}^{\text{3}}}{\text{ of 1.0 mol}}\,{\text{d}}{{\text{m}}^{ - {\text{3}}}}{\text{ NaOH}}\)
Markscheme
A
