Question

Which of the following solutions have the same concentration?
(i) 20 g of NaOH in 200 mL of solution(ii) 0.5 mol of KCl in 200 mL of solution(iii) 40 g of NaOH in 100 mL of solution

Answer 1

$\boxed{Molarity\:Of\:Solution\:=\:weight\:x\:1000/ \:Mass\:x\:Volume(mL)}$

(a) 20 g of NaOH in 200 mL of solution

$Molarity = \frac{20\:x\:1000}{40\:x\:200}$

$= 2.5\:M$

(b) 0.5 mol of KCl in 200 mL of solution

$Molarity = \frac{0.5\:x\:1000}{200\\\\} \\= 2.5\:M$

(c) 40 g of NaOH in 100 mL of solution

$Molarity = \frac{40\:x\:1000}{40\:x\:100}$

$10\:M$

(d) $Molarity = \frac{20\:x\:1000}{56\:x\:200}$

$= 1.785\:M$

Therefore, option (a) and option (c) have the same amount of concentration.