Question

Calculate molarity of the solution if 4 g noah dissolves in 500mL water

Answer 1

Answer:

0.05M

Explanation:

molarity = no of moles (solute)/volume of solution (ltr)

no of moles = given mass/ molar mass

n = 4/40 = 1/40

M = n/V

M = 1/40/1/2

M = 1/20

M = 0.05M

Answer 2

Answer:

$\displaystyle{Molarity=0.2 \ M}$

Explanation:

$\displaystyle{Given \ mass \ is \ 4 \ g}\\\\\\\displaystyle{Molar \ mass \ of \ NaOH=23+16+1=40 \ g}\\\\\\\displaystyle{No. \ of \ moles=\dfrac{Given \ mass}{Molar \ mass}}\\\\\\\displaystyle{No. \ of \ moles=\dfrac{4}{40}}\\\\\\\displaystyle{No. \ of \ moles=0.1 \ moles}$

$\displaystyle{Molarity=\dfrac{No. \ of \ moles \ of \ solute}{volume \ of \ solution(L)}}\\\\\\\displaystyle{Molarity=\dfrac{No. \ of \ moles \ of \ solute}{volume \ of \ solution(mL)}\times1000}\\\\\\\displaystyle{Putting \ value \ here }\\\\\\\displaystyle{Molarity=\dfrac{0.1}{500}\times1000}\\\\\\\displaystyle{Molarity=0.1\times2 \ M}\\\\\\\displaystyle{Molarity=0.2 \ M}$

Thus we get Molarity of solution is 0.2 Molar .