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Question 19M.2.sl.TZ2.5b(ii)

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.2.sl.TZ2.5b(ii)
Level sl Paper 2 Time zone TZ2
Command term Calculate Question number b(ii) Adapted from N/A
b(ii).
[Maximum mark: 2]
19M.2.sl.TZ2.5b(ii)

Carbonated water is produced when carbon dioxide is dissolved in water under pressure.

The following equilibria are established.

Soda water has sodium hydrogencarbonate, NaHCO3, dissolved in the carbonated water.

(b(ii))

100.0 cm3 of soda water contains 3.0 × 10−2 g NaHCO3.

Calculate the concentration of NaHCO3 in mol dm−3.

[2]

Markscheme

«molar mass of NaHCO3 =» 84.01 «g mol–1»  [✔]

«concentration =  3.0 × 10 − 2  g 84.01  g mo l − 1 × 1 0.100  d m 3 = » 3.6 × 10–3 «mol dm–3»  [✔]

 

Note: Award [2] for correct final answer.

Examiners report

Very well answered. Most candidates calculated the molar concentration correctly.

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