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Acids and bases (A-level only)

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Question 7

Calcium hydroxide is relatively insoluble in water, but it reacts readily with dilute nitric acid.

Ca(OH)2(s)+2HNO3(aq)→Ca(NO3)2(aq)+2H2O(l) \text{Ca(OH)}_2(\text{s}) + 2\text{HNO}_3(\text{aq}) \rightarrow \text{Ca(NO}_3)_2(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) Ca(OH)2​(s)+2HNO3​(aq)→Ca(NO3​)2​(aq)+2H2​O(l)

An experimentalist adds 250 cm3 of 0.0800 mol dm-3 nitric acid to 1.15 g of solid calcium hydroxide.

a.

Show, by calculation, that the calcium hydroxide is in excess.

[3]
b.

The final mixture contains a saturated solution of Ca(OH)2\text{Ca(OH)}_2Ca(OH)2​ at 298 K.

At 298 K:

  • the solubility of Ca(OH)2\text{Ca(OH)}_2Ca(OH)2​ in this solution is 1.48 g dm-3
  • Kw=1.00×10−14 mol2 dm−6K_w = 1.00 \times 10^{-14}\text{ mol}^2\text{ dm}^{-6}Kw​=1.00×10−14 mol2 dm−6

Calculate the pH of this solution. Give your answer to two decimal places. (Assume the molar mass of Ca(OH)2\text{Ca(OH)}_2Ca(OH)2​ is 74.1 g mol-1.)

[4]

Acids and bases (A-level only) Questions

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  3. /Acids and bases (A-level only)