| Date | May 2009 | Marks available | 1 | Reference code | 09M.1.hl.TZ2.27 |
| Level | HL | Paper | 1 | Time zone | TZ2 |
| Command term | Identify | Question number | 27 | Adapted from | N/A |
Question
Ammonia acts as a weak base when it reacts with water. What is the \({K_{\text{b}}}\) expression for this reaction?
A. \(\frac{{[{\text{NH}}_4^ + ][{\text{O}}{{\text{H}}^ - }]}}{{[{\text{N}}{{\text{H}}_3}][{{\text{H}}_2}{\text{O]}}}}\)
B. \(\frac{{[{\text{N}}{{\text{H}}_3}{\text{][}}{{\text{H}}_2}{\text{O]}}}}{{{\text{[NH}}_4^ + {\text{][O}}{{\text{H}}^ - }{\text{]}}}}\)
C. \(\frac{{[{\text{N}}{{\text{H}}_3}]}}{{[{\text{NH}}_4^ + ][{\text{O}}{{\text{H}}^ - }]}}\)
D. \(\frac{{[{\text{NH}}_4^ + ][{\text{O}}{{\text{H}}^ - }]}}{{[{\text{N}}{{\text{H}}_3}]}}\)
Markscheme
D
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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