Question

What volume of water is to be added to 100 cm3
of 0.5 M NaOH solution to make it 0.1 M solution?
(1) 200 cm3
(2) 400 cm3
(3) 500 cm3
(4) 100 cm3 ​

Answer 1

Answer:

(3) 500cm3

Explanation:

Vol. of NaOH solution = 10⁻³ × 10²    (as 1cm³ = 10⁻³ l)

Molarity(M)  = No of moles

                Vol of solution

No of moles = M/ Vol of solution

                     = 0.5 × 10⁻¹

                     = 5 × 10⁻¹ × 10⁻¹

                     = 5 × 10⁻² mol

For 0.1 M of NaOH solution

                   0.1 = 5 × 10⁻² / Vol of solution

Vol of solution = 5 × 10⁻² / 10⁻¹

                         = 5 × 10⁻² × 10

                         = 5 × 10⁻¹ l

                         = 500 ml