Question

How many grams of KOH will be required to prepare 250 ml 0.05 M solution.

Answer 1

Solution :

Given :-

Volume of solution = 250ml

Conc. of solution = 0.05M

To Find :-

Mass of KOH requires to prepare require solution.

Concept :-

Molarity of solution is given by ratio of moles of solute to the volume of solution.

Mathematically,

$\boxed{\bf{\pink{Molarity=\dfrac{w\times 1000}{Mw\times V_{ml}}}}}$

• w denotes weight of solute
• Mw denotes molecular weight of solute
• V denotes volume of solution

Mw of KOH = 1(K)+1(O)+1(H) = 39+16+1 = 56g/mol

Calculation :-

$\implies\sf\:0.05=\dfrac{w\times 1000}{56\times 250}\\ \\ \implies\sf\:w=\dfrac{0.05\times 56}{4}\\ \\ \implies\underline{\boxed{\bf{\orange{weight=0.7\:g}}}}$

Answer 2

Volume of soln=250ml=0.25 L

Molarity= 0.05 M

We know that,

$molarity = \frac{moles \: koh}{vol \: soln}$

$moles \: of \: koh = 0.25 \times 0.05 \\ moles \: of \: koh =0.0125$

molar mass of KOH =56g

$mass \: of \: koh = 0.0125 \times 56 \\ mass \: \: of \: koh =0.7g$

i hope this helps ( ╹▽╹ )