DP Chemistry (last assessment 2024)

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Question 19M.2.hl.TZ1.3e

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Date May 2019 Marks available [Maximum mark: 3] Reference code 19M.2.hl.TZ1.3e
Level hl Paper 2 Time zone TZ1
Command term Write Question number e Adapted from N/A
e.
[Maximum mark: 3]
19M.2.hl.TZ1.3e

This question is about sodium and its compounds.

(e)

Write equations for the separate reactions of solid sodium oxide and solid phosphorus(V) oxide with excess water and differentiate between the solutions formed.

Sodium oxide, Na2O:

Phosphorus(V) oxide, P4O10:

Differentiation:

 

 

[3]

Markscheme

Sodium oxide:
Na2O(s) + H2O(l) → 2NaOH (aq)      [✔]

Phosphorus(V) oxide:
P4O10 (s) + 6H2O(l) → 4H3PO4 (aq)     [✔]

Differentiation:
NaOH/product of Na2O is alkaline/basic/pH > 7 AND H3PO4/product of P4O10 is acidic/pH < 7     [✔]

Examiners report

An average of 1.1 out of 3 earned here. Many candidates could write a balanced equation for the reaction of sodium oxide with water but not phosphorus(V) oxide. Mediocre performance in identifying the acid/base nature of the solutions formed.

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