Question

How much waler should be added to 30ml of
alcohol so as to obtain 7.5% alcohol solution.​

Answer 1

Given:-

→ Volume of alcohol = 30 mL

→ Concentration [v/v %] = 7.5%

To find:-

→ Amount [volume] of water to be added.

Solution:-

Let the required volume of water be 'x' mL.

It is clear that, alcohol is solute and water is solvent. We are given with the volume of solute and concentration of the solution. So firstly, let's calculate the total volume of the solution.

Volume of a solution :-

= Volume of solute + Volume of solvent

= 30 mL + x mL

= (30 + x) mL

Concentration of a solution [v/v %] :-

= Vol.of solute/Vol.of solution × 100

Substituting values,we get :-

=> 30/(30 + x) × 100 = 7.5

=> 30(100) = 7.5(30 + x)

=> 3000 = 225 + 7.5x

=> 7.5x = 3000 - 225

=> 7.5x = 2775

=> x = 2775/7.5

=> x = 370 mL

Thus, 370mL of water should be added.

Answer 2

Answer:

hope it helps you.....