Question

1)Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory to standardize strong base solutions. It has the unwieldy formula of KHC₈H₄O₄. This is often written in shorthand notation as KHP.

How many grams of KHP are needed to exactly neutralize 21.1 mL of a 0.399 M potassium hydroxide solution ?

grams KHC₈H₄O_4.

2) Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory to standardize strong base solutions. It has the unwieldy formula of KHC₈H₄O₄. This is often written in shorthand notation as KHP.

What volume of a 0.363 M barium hydroxide solution is needed to exactly neutralize 4.46 grams of KHP ?

ANSWER:   mL barium hydroxide

Answer 1

1) Let us first find out the number of moles of NaOH present in 21.1 mL of 0.399 M solution. As the solution is 0.399 M, it means that there are 0.399 moles of NaOH present in 1000 mL of solution. Therefore, we can consider

1000 mL of solution = 0.399 moles of NaOH

For, 21.1 mL of solution = (21.1 x 0.399) /1000 = 0.0084 moles

As the KHP is a monoprotic acid, to neutralize 0.0084 moles of NaOH same number of moles of KHP will be required.

The molar mass of KHP is 204.22 g/mol.

Therefore mass of KHP can be calculated using following formula,

Mass of KHP = moles of KHP x molar mass of KHP

= 0.0084 mol x 204.22 g/mol

= 1.71 g

Thus answer is 1.71 g

2) Let us first calculate the number of moles of KHP in 4.46 grams.

Number of moles of KHP = Weight of KHP / Molecular weight of KHP

= 4.46 g / 204.22 g/mol

= 0.0218 moles

As Barium hydroxide is dibasic, the number of moles of barium hydroxide required will be half of the number of moles of KHP.

Therefore number of moles of barium hydroxide required = 0.0218 / 2 = 0.0109 moles

As the solution of barium hydroxide is 0.363 M, it means that there are 0.363 moles of barium hydroxide present in 1000 mL. Therefore we can consider

0.363 moles = 1000 mL

for 0.0109 moles = (0.0109 x 1000) / 0.363 mL

= 30 mL

Thus answer is 30 mL.