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Calculate the Ph of the Following Solutions: 0.3 G of Ca(Oh)2 Dissolved in Water to Give 500 Ml of Solution. - CBSE (Science) Class 11 - Chemistry

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Question

Calculate the pH of the following solutions:

0.3 g of Ca(OH)dissolved in water to give 500 mL of solution.

Solution 1

For 0.3 g of Ca(OH)2 dissolved in water to give 500 mL of solution:

`Ca(OH)_2 -> Ca^(2+) + 2OH^(-)`

`[Ca(OH)_2] = 0.3 xx 1000xx500= 0.6 M`

`[OH_aq^-] = 2xx[Ca(OH)_(2aq)] = 2xx 0.6`

= 1.2 M

`[H^+] = (K_w)/([OH_(aq)^-])`

`=(10 - 14)/1.2 M`

`= 0.833 xx 10^(-14)`

`pH = -log (0.833 xx 10^(-14))`

`= - log (8.33 xx 10^(-13))`

`= (-0.902 + 13)`

= 12.098

Solution 2

Molar conc of `Ca(OH)_2` = `(0.3 g)/((40 + 34 )g mol^(-1)) xx 1/(0.5 L) = 8.11 xx 10^(-3) M`

`Ca(OH)_2 -> Ca^(2+) + 2OH` 

`[OH^-] = 2(Ca(OH)_2) = 2xx(8.11 xx 10^(-3)) M = 16.22 xx 10^(-3) M`

`pOH = -log (16.22 xx 10^(-3)) = 3 - 1.2101 = 1.79`

`pH = 14 - 1.79 = 12.21` 

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Solution Calculate the Ph of the Following Solutions: 0.3 G of Ca(Oh)2 Dissolved in Water to Give 500 Ml of Solution. Concept: Ionization of Acids and Bases - The pH Scale.
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