You are going to standardize your sodium hydroxide by titrating with potassium h

Question

You are going to standardize your sodium hydroxide by titrating with potassium hydrogen phthalate. As an example, you dissolve 0.3365 g of potassium hydrogen phthalate, otherwise known as KHP (KHC8H4O4) in water in a 250.0 mL Erlenmeyer flask and then add phenolphthalein indicator. You then titrate with your sodium hydroxide solution, which is in a buret, and you determine that the equivalence point is at 12.44 mL of your sodium hydroxide solution. Determine the molarity of your sodium hydroxide solution. What color will the solution of potassium hydrogen phthalate turn to determine when the equivalence point has been reached?

Explanation / Answer

Molar mass of KHP = 204 g/mole

thus, moles of KHP in 0.3365 g of it = mass/molar mass = 0.3365/204 = 0.00165

Thus, moles of NaOH required = moles of KHP = 0.00165

Molarity of NaOH solution = moles/volume of solution in litres = 0.00165/0.01244 = 0.133 M

The color will change to pink at the point of equivalence.

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