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24/10/2021 11:17 am
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The concentration of hydroxyl ion in a solution left after mixing 100 mL of 0.1 M MgCl2 and 100 mL of 0.2 M NaOH
(Ksp of Mg(OH)2 = 1.2 x 10-11) is
(a) 2.8 x 10-4
(b) 2.8 × 10-3
(c) 2.8 x 10-2
(d) 2.8 x 10-5
1 Answer
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24/10/2021 11:29 am
Correct answer: (a) 2.8 x 10-4
Explanation:
MgCl2 + 2NaOH → Mg(OH)2 + 2NaCl
100x0.1 100x0.2 0 0 Initial moles
0 0 10 20 After mixing
∴ Ksp = \(\Big[\frac{10}{200}\Big]\)\(\Big[\frac{20}{200}\Big]^2\)
= 5 x 10-4
But actually Ksp of Mg(OH)2 = 1.2 x 10-11
∴ 4S3 = 1.2 x 10-11
Find S then [OH-] = 2S which is 2.8 x 10-4
This post was modified 3 years ago by Mayank1444