Question

a solution of NaOH(molar mass 40g mol-1 )was prepared by dissolve in 1.6g of NaOH in 500cm3 of water calculate molarity of NaOH solution

Answer 1

Molarity(M) = w × 1000 / GMW × V

where,

w = given weight of the solute = 4g

GMW = Gram Molecular Weight of the solute = 40g

V = Volume of the solution in ml. = 250 ml

So,

M of NaOH

= 4 × 1000 / 40 × 250

= 0.4 M

Answer 2

ANSWER

1 mol of NaOH has a mass of 40g. So

Moles of NaOH=1.6g of NaOH×

1 mol NaOH/ 40g NaOH =0.04 mol NaOH

Litres of solution =500ml solution ×

1L Solution/1000ml Solution =0.5 L Solution

Molarity = moles of Solute/litres of solution

= 0.04 /0.5 mol/L

=0.08 mol/L