DP Chemistry (last assessment 2024)

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Question 17N.2.hl.TZ0.e

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Date November 2017 Marks available [Maximum mark: 2] Reference code 17N.2.hl.TZ0.e
Level hl Paper 2 Time zone TZ0
Command term Suggest Question number e Adapted from N/A
e.
[Maximum mark: 2]
17N.2.hl.TZ0.e

A student titrated two acids, hydrochloric acid, HCl (aq) and ethanoic acid, CH3COOH (aq), against 50.0 cm3 of 0.995 mol dm–3 sodium hydroxide, NaOH (aq), to determine their concentration. The temperature of the reaction mixture was measured after each acid addition and plotted against the volume of each acid.

Suggest why the enthalpy change of neutralization of CH3COOH is less negative than that of HCl.

[2]

Markscheme

CH3COOH is weak acid/partially ionised

energy used to ionize weak acid «before reaction with NaOH can occur»

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