chemistry :)))

C harlotte Davis

2015-06-03 9:25 am

1) In an experiment, 10cm3 of 1.0M sulphuric acid are mixed with 30cm3 of 0.5M sodium hydroxide solution. Which of the following statements concerning this experiments is/are correct?
(a)0.015mole of water is formed.
(b)The pH of the resulting mixture is greater han 7.
(c) After water is completely evaporated from the resulting mixture, pure sodium sulphate solid an be obtained.
****for each answer please explain why.

回答 (1)

用戶26240

2015-06-03 7:01 pm

✔ 最佳答案

(1)
H2SO4 + 2N aOH → N a2SO4+ 2H2O

No. of moles of H2SO4 added = 1 × (10/1000) = 0.01 mol
No. of moles of N aOH added = 0.5 × (30/1000) = 0.015 mol

When 0.015 mol of N aOH is completely reacted,
no. of moles of H2SO4 needed = 0.015 × (1/2) = 0.0075 mol< 0.01 mol

Hence, H2SO4 is in excess, and N aOH is the limitingreactant (completely reacted).
No. of moles N aOH reacted = 0.015 mol
No. of moles of H2O formed = 0.015 × (2/2) = 0.015 mol
...... (a) is correct.

As H2SO4 is in excess, the resulting solution is acidic.
Hence, pH of the resulting solution is lower than 7.
...... (b) is incorrect.

Sulphuric acid is in excess, which has a much higher boiling point (338°C) thanwater . After water is completely evaporated, a mixture of sodium sulphate andsulphuric acid is obtained.
..... (c) is incorrect.

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