Question

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A1 liter solution contains 0.526 M hydrofluoric acid and 0.395 M potassium fluoride. Addition of 0.434 moles of hydrochloric acid will: (Assume that the volume does not change upon the addition of hydrochloric acid.) Raise the pH slightly Lower the pH slightly Raise the pH by several units Lower the pH by several units Not change the pH Exceed the buffer capacity Submit Answer Retry Entire Group 2 more group attempts remaining

pKa values

Answer 1

Raise the pH slightly Lower the pH slightly Raise the pH by several units ower the pH by several units Not change the pH Exceed the buffer capacity V

Moles of KF = 0.395 M x 1 L = 0.395 mol

Moles of HCl added = 0.434 mol

0.395 mol of KF will react with 0.395 mol of HCl.

Excess HCl after reaction = (0.434 - 0.395) mol = 0.039 M

Hence, the pH will change drastically as HCl will exceed the buffer capacity of the solution.

Hence, after the addition of HCl, there will be no KF left to maintain buffering action of the solution.

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Raise the pH slightly Lower the pH slightly Raise the pH by several units Lower the pH by several units Not change the pH Exceed the buffer capacity

Moles of HCN = 0.396 M x 1 L = 0.396 mol

Moles of NaOH added = 0.436 mol

0.396 mol of HCN will react with 0.396 mol of NaOH.

Excess NaOH after reaction = (0.436 - 0.396) mol = 0.040 M

Hence, the pH will change drastically as NaOH will exceed the buffer capacity of the solution.

Hence, after the addition of NaOH, there will be no HCN left to maintain buffering action of the solution.

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False A. The number of moles of NH, will increase. True B. The number of moles of NH, will increase. False C. The equilibrium concentration of H3O+ will remain the same. False - D. The pH will remain the same. True , E. The ratio of (NH3] [NH,*] will decrease.

Amount of NH₃ will decrease on addition of HCl as HCl converts NH₃ to NH₄⁺. Hence, the concentration of NH₄⁺ will increase. The increase in concentration NH₄⁺ implies that increase in H₃O⁺ concentration. Increase in H₃O⁺ concentration implies decrease in pH.  The increase in concentration NH₄⁺ and the decrease in NH₃ concentration implies the decrease of [NH₃]/[NH₄⁺] ratio.

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True » A. The number of moles of HCN will increase. True B. The number of moles of CN will decrease. C. The equilibrium concentration of H2O will increase. True False D. The pH will remain the same. False E. The ratio of (HCN CN) will decrease.

The amount of HCN will increase on addition of HClO₄ as HClO₄ converts KCN to HCN. Hence, the amount of CN^- will decrease. The increase in concentration HCN implies that increase in H₃O⁺ concentration. Increase in H₃O⁺ concentration implies decrease in pH.  The increase in concentration HCN and the decrease in KCN concentration implies the increase of [KCN]/[HCN] ratio.