Question

How many grams of NaOH should be added to water to prepare 250 ml solution of 2 M NaOH ?

Answer 1

Molar mass of NaOH (M) = 40 g mol​-1
Volume of solution (V) = 250 mL
Molarity of NaOH solution = 2 M
Molarity = w×1000M×V
w (Mass of NaOH ) = 2×40×2501000 = 20 g 
Hence , 20 g of NaOH will be required

Answer 2

Answer:

The number of grams of NaOH to be added to water to prepare 250ml solution of 2M NaOH is 20 grams.

Explanation:

Molarity is defined as the ratio of the amount of solute to the solution or the amount of moles dissolved the amount of solvent in the total moles of total solution.  

Molarity or $\bold{\mathrm{M}=\frac{\text { Moles of solute(NaOH } )}{\text { Total Solution (litres) }}}$

$2 \mathrm{M}=\frac{\text { Moles of solute }}{250 \mathrm{ml}}2 \mathrm{M}=\frac{\text { Moles of } \mathrm{NaOH}}{0.25}$

2M×0.25= Moles of NaOH

0.5 M= Moles of NaOH

We also know that the molar mass or Molarity of NaOH= 40gm  

0.5 M= 40gm

M=40÷0.5 gm= 20gm

So, 20 gm of NaOH must be added to water to get 2 M NaOH