DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ1.21a

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.3.hl.TZ1.21a
Level hl Paper 3 Time zone TZ1
Command term Formulate Question number a Adapted from N/A
a.
[Maximum mark: 1]
19M.3.hl.TZ1.21a

Mild heartburn is treated with antacids such as calcium carbonate.

(a)

Formulate an equation for the neutralization of stomach acid with calcium carbonate, CaCO3 (s).

[1]

Markscheme

CaCO3 (s) + 2HCl (aq) → CO2 (g) + CaCl2 (aq) + H2O (l)   [✔]

 

Note: Accept balanced ionic equations involving “H+” or “H3O+”.

Do not accept “H2CO3”.

Examiners report

Responses were mixed with some candidates easily writing an equation for the neutralization of stomach acid with CaCO3. Others failed to score for having incorrect products such as H2CO3 or CaCl, or for using sulfuric acid instead of hydrochloric for stomach acid.

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