Question

A 10.00 mL sample of a 1.07 M solution of potassium hydrogen phthalate (KHP, formula mass = 204.22 g/mol) is diluted to 250.0 mL. What is the molarity of the final solution?

Answer 1

Answer:

[KHP] = 0.0428M

Explanation:

2 methods to calculate concentration after dilution

1. Use dilution equation

Molarity of concentrate (M₁) x Volume of Concentrate (V₁)

           =    Molarity of dilute (M₂) x Volume of dilute (V₂)

M₁ x V₁ = M₂ x V₂ => M₂ = M₁ x V₁ / V₂ = (1.07M)(10ml)/(250ml) = 0.0428M

2. Concentration Equation

moles KHPh = Molarity (M)  x  Volume (V) = 1.07M x 0.010L =0.0107 moles KHP

Concentration KHP = moles solute / volume of solution in Liters

= 0.0107 moles KHP / 0.25L = 0.0428M