volume in ML and concentration

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.

What volume of a 0.415 M barium hydroxide solution is needed to exactly neutralize 4.33 grams of KHP ?

ANSWER:___________  mL barium hydroxide

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.

If 5.57 grams of KHP are needed to exactly neutralize 32.6 mL of a barium hydroxide solution, what is the concentration of the base solution ?

ANSWER:  ________M barium hydroxide

Answer 1

2KHC₈H₄O₄(aq) + Ba(OH)₂(aq) ---> BaC₈H₄O₄(s) + K₂C₈H₄O₄(aq) + 2H₂O(l) ... balanced equation

moles KHP = 4.33 g KHP x 1 mol/204.23 g = 0.0212 moles KHP

moles Ba(OH)2 needed = 0.0212 moles KHP x 1 mol Ba(OH)2/2 moles KHP = 0.0106 moles

volume Ba(OH)2 needed: 0.415 mol/L (x L) = 0.0106 moles and x = 0.0255 L = 25.5 mls barium hydroxide

moles KHP = 5.57 g x 1 mol/204.23 g = 0.0273 moles

moles Ba(OH)2 = 0.0273 moles KHP x 1 mole Ba(OH)2/2 moles KHP = 0.0136 moles Ba(OH)2

Concentration of barium hydroxide = 0.0136 moles/0.0326 L = 0.418 M barium hydroxide