Question

35
28. Molarity of NaOH in 200 mL of an aqueous solution
of it is 1M, find the change in molarity if 2g of
NaOH is added to it.
(1) 1.25 M
(2) 0.25 M
(3) 0.50 M
(4) 0.75 M​

Answer 1

Answer:

The answer is (1)

Soln in the attachment above.....

Answer 2

Answer:

Change in molarity of the solution is 0.25 M.

Explanation:

Molarity of the solution = 1 M

Volume of the solution = 200 mL = 0.2 L

Moles of NaOH = n

$1 M=\frac{n}{0.200 L}$

n = 0.200 mol

Mass of NaOH added = 2 g

Moles of NaOH added = $\frac{2}{40 g/mol}=0.05 mol$

Total moles of NaOH = 0.2 mol + 0.05 mol =  0.25 mol

New molarity of the solution:

$\frac{0.25 mol}{0.200 L}=1.25 mol/l$

Change in molarity of the solution : 1.25 mol - 1 M = 0.25 M