Question

Calculate the molarity of naoh in the solution prepared by dissolving 4g in enough water to form 200ml of the solution

Answer 1

Answer :

Given -

• Mass of solute (NaOH) = 4 g.
• Volume of solution = 200 mL.

To Find -

• Molarity ?

Solution -

Molar mass of NaOH = 23 u + 18 u + 1 u = 40 u = 40 g/mol.

Volume of solution in L = 200 mL = 200/1000 = 0.2 L.

Now, we know that, No. of moles of NaOH = Given mass/Molar mass.

⇒ No. of moles = 4/40

⇒ No. of moles = 1/10

⇒ No. of moles = 0.1 mol.

FORMULA : Molarity = No. of moles of solute/Volume of solution.

⇒ Molarity = 0.1/0.2

⇒ Molarity = 0.5 M.