Concentration and pH?
2016-01-11 1:34 pm
Calculate [OH-], [H3O+] and pH in saturated Ba(OH)2(aq), which contains 3.9 g Ba(OH)28H2O per 100 mL of solution.
回答 (1)
2016-01-11 1:49 pm
Molar mass of Ba(OH)2•8H2O = 137.3 + 1×18 + 16×10 = 315.3 g/mol
No. of moles of Ba(OH)2•8H2O = (3.9 g) / (315.3 g/mol) = 0.01237 mol
No. of moles of OH- ions = 0.01237 × 2 = 0.0247 mol
[OH-] = (0.0247 mol) / (100/1000 L) = 0.247 M
[H3O+] = Kw / [OH-] = (1 × 10^-14 M^2) / (0.247 M) = 4.05 × 10^-14 M
pH = -log[H3O+] = -log(4.05 × 10^-14) = 13.4
No. of moles of Ba(OH)2•8H2O = (3.9 g) / (315.3 g/mol) = 0.01237 mol
No. of moles of OH- ions = 0.01237 × 2 = 0.0247 mol
[OH-] = (0.0247 mol) / (100/1000 L) = 0.247 M
[H3O+] = Kw / [OH-] = (1 × 10^-14 M^2) / (0.247 M) = 4.05 × 10^-14 M
pH = -log[H3O+] = -log(4.05 × 10^-14) = 13.4
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