| Date | November 2011 | Marks available | 1 | Reference code | 11N.1.hl.TZ0.27 |
| Level | HL | Paper | 1 | Time zone | TZ0 |
| Command term | Identify | Question number | 27 | Adapted from | N/A |
Question
Consider the equation for the dissociation of water:
\[\begin{array}{*{20}{l}} {{{\text{H}}_2}{\text{O(l)}} \rightleftharpoons {{\text{H}}^ + }{\text{(aq)}} + {\text{O}}{{\text{H}}^ - }{\text{(aq)}}}&{\Delta H = + 57.3{\text{ kJ}}\,{\text{mo}}{{\text{l}}^{ - 1}}} \end{array}\]
Which statement is correct?
A. The pH of pure water is always 7.
B. At temperatures above 298 K the pH of pure water is below 7.
C. At temperatures above 298 K the pH of pure water is above 7.
D. \({K_{\text{w}}}\) decreases with increasing temperature.
Markscheme
B
Examiners report
[N/A]
Syllabus sections
Additional higher level (AHL) » Topic 18: Acids and bases » 18.2 Calculations involving acids and bases
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