DP Chemistry (last assessment 2024)
Question 17N.2.sl.TZ0.c
| Date | November 2017 | Marks available | [Maximum mark: 2] | Reference code | 17N.2.sl.TZ0.c |
| Level | sl | Paper | 2 | Time zone | TZ0 |
| Command term | Calculate | Question number | c | Adapted from | N/A |
c.
[Maximum mark: 2]
17N.2.sl.TZ0.c
A student titrated an ethanoic acid solution, CH3COOH (aq), against 50.0 cm3 of 0.995 mol dm–3 sodium hydroxide, NaOH (aq), to determine its concentration.
The temperature of the reaction mixture was measured after each acid addition and plotted against the volume of acid.
Calculate the concentration of ethanoic acid, CH3COOH, in mol dm–3.
[2]
Markscheme
ALTERNATIVE 1
«volume CH3COOH =» 26.0 «cm3»
«[CH3COOH] = 0.995 mol dm–3 \( \times \frac{{50.0\,{\text{cm3}}}}{{26.0\,{\text{cm3}}}} = \)» 1.91 «mol dm−3»
ALTERNATIVE 2
«n(NaOH) =0.995 mol dm–3 x 0.0500 dm3 =» 0.04975 «mol»
«[CH3COOH] = dm3 =» 1.91 «mol dm–3»
Accept values of volume in range 25.5 to 26.5 cm3.
Award [2] for correct final answer.
