%%% asked in Science & MathematicsChemistry · 1 year ago

Calculate PH of 50 ml mixture of 0.1M HCl and 0.05M weak acid (HA,Ka=10*-5) after addition of 5ml 0.1ml KOH ?

1 Answer

  • 1 year ago
    Favourite answer

    Because the concentration of HCl is greater than that of the weak acid, the pH of the solution is dictated by the concentration of HCl. and the presence of the weak acid can be ignored.

    So, in the initial solution, the pH = 1.

    Now, in that solution, that are 0.050 L X 0.1 mol/L = 5X10^-3 moles HCl. To that you are adding 5X10^-4 mol KOH. That will react with the HCl leaving 4.5X10^-3 mol HCl, now in a volume of 55 mL. So, the molarity of HCl is now 4.5X10^-3 mol / 0.055 L = 0.082 M HCl. This solution has a pH = = 1.09

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