Question

Q. A solution has 20% w/w NaOH and density of solution is 1.2 g/ml then find out molarity:-​

Answer 1

Answer:

Explanation I hope by this soln you will find out the answer more easily

I have done it roughly

Answer 2

Answer :

Given -

• The w/w % of the solution = 20%
• Density of the solution of NaOH = 1.2 g/ml

To Find -

• Molarity ?

Solution -

We are given, w/w % = 20%.

Hence, 20 g of NaOH is in 100 g of solution.

Now, Density = Mass/Volume.

⇒ 1.2 = 100/Volume

⇒ Volume = 100/1.2

⇒ Volume = 83.33 mL = 83.33/1000 = 0.08333 L

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

Now, Molarity = No. of moles of solute/Volume of solution in litres.

⇒ Molarity = (Total mass/Molar mass)/Volume of solution in L

⇒ Molarity = (20/40)/0.08333

⇒ Molarity = (1/2)/0.08333

⇒ Molarity = 0.5/0.08333

⇒ Molarity = 6 M.