16. A solution is made by adding 0.500 mols of NaF and 0.500 mols of KCN...

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16. A solution is made by adding 0.500 mols of NaF and 0.500mols of KCN to 0.75L of water. What will the pH of this solutionbe? You may need to refer to the Ka/Kb table attached to this examfor this problem. Give your answer to two decimalplaces.Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â

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4.1 Ratings (507 Votes)

F- + H2O ----------------->Â Â HF + OH-

0.5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0Â Â Â Â Â Â Â Â 0

0.5-xÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â xÂ Â Â Â Â Â Â Â Â x

Kb = x^2 / 0.5-x

1.59 x 10^-11 = x^2 / 0.5-x

x = 2.82 x 10^-6

[OH-] = 2.82 x 10^-6 M

CN- + H2OÂ Â ------------------> HCN + OH-

0.5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 0Â Â Â Â Â Â Â Â Â Â 0

0.5 -xÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â xÂ Â Â Â Â Â Â Â Â Â Â x

Kb = x^2 / 0.5-x

1.59 x 10^-5 = x^2 / 0.5 - x

x = 2.81 x 10^-3

[OH-] = 2.81 x 10^-3 M

total [OH-] = 2.82 x 10^-6 + 2.81 x 10^-3

= 2.81 x 10^-3 M

pOH = 2.55

pH = 11.45

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16. A solution is made by adding 0.500 mols of NaF and 0.500 mols of KCN...

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