Question

How much of water should be added to 15g of salt to obtain 15% salt solution?

Answer 1

The mass by mass percentage of a solution is given by the following relation



where mass of solution = mass of solute + mass of solution

Here, mass of the solute (i.e. salt) = 15 g and the required concentration of the solution is 15 %.

Let the mass of water be a grams.

So,

15 = [15 / (15 + a)] X 100

Solving for a, we get

a = (100 - 15)g = 85 g

Answer 2

Answer:

85 mL

Explanation:

Given :

Mass of solute = 15 g

Mass % = 15 g

We know :

Mass % = ( mass of solute / mass of solution ) × 100

We can write :

Mass of solution = mass of solute + mass of solvent

Let :

Mass of solvent = y gram :

= > 15  = ( 15 ) / ( 15 + y ) × 100

= > 1  = ( 1 ) / ( 15 + y ) × 100

= > 15 + y = 100

= > y = 85 g

We know :

Density = Mass / Volume

= > Volume = mass / density :

Density of water = 1 g / mL

= > Volume = 85 / 1 mL

= > Volume = 85 mL

Therefore , we get required answer.