Usually potassium hydrogen phthalate is kept very pure. But Stu Dent thinks the

Question

Usually potassium hydrogen phthalate is kept very pure. But Stu Dent thinks the bottle of potassium hydrogen phthalate has been accidently mixed with sodium chloride salt. He decides to use a titration to determine the amount of potassium hydrogen phthalate present. He weight 2.3854 g of the contaminated potassium hydrogen phthalate mixture. The titration uses 17.47 mL of 0.5000 m sodium hydroxide. Use the titration volume and concentration to calculate the moles of potassium hydrogen phthalate actually reacted. Then use the molar mass (2.4.2 g/mol) to calculate the mass of potassium hydrogen phthalate actually reacted. Enter the mass to 4 significant digits with units of g. Mass: Calculate the percentage of potassium hydrogen phthalate in the contaminated sample by dividing the mass of potassium hydrogen phthalate actually reacted by the original mass of the sample and multiply by 100 to make a percentage. Enter the percentage of potassium hydrogen phthalate to 4 signific

Explanation / Answer

The reaction between KHP and NaOH is as follows:

KHC8H4O4(aq) + NaOH(aq) KNaC8H4O4(aq) + H2O(l)

Given that;

17.47 mL of 0.5000 M NaOH

Number of moles of NaOH = 0.01747 L* 0.5000 mol/ L

= 8.735*10^-3 Mol

According to balance reaction calculate the number of moles KHP as follows:

8.735*10^-3 Mol NaOH * 1 mol KHP / 1 mol NaOH

=8.735*10^-3 Mol KHP

Now convert the mass of KHP by its molar mass:

8.735*10^-3 Mol KHP*204.2 g/ mol

= 1.7837 g Potassium hydrogen phthalate

% of KHP = 1.7837 g Potassium hydrogen phthalate * 100

                      2.3854 g Potassium hydrogen phthalate

= 74.7752%

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