Question

What is the molar concentration of an aqueous solution that has 200g of Iron (II) Chloride dissolved in 450mL of water?

(convert to moles then solve for Molarity)

Answer 1

We are given:

200 grams of FeCl₂ in 450 mL of water

Number of Moles of FeCl₂ in 450 mL:

Molar mass of FeCl₂ = 127 grams/mol (approx)

Number of moles = Given mass / molar mass

replacing the variables

Number of moles = 200 / 127

Number of moles = 1.57 moles

Number of Moles of FeCl₂ in 1 L (Molarity):

We know that in 450 mL of the solution, we have 1.57 moles

Molarity of the solution = Number of moles / Volume of solution (in L)

Molarity of the solution = 1.57 / 0.45

Molarity of the solution = 3.489 M