Section 1: Calculating Percent Weight in Volume
If you know the amount of a component present and the volume of product involved, you can calculate the % w/v of the component.
A solution contains 2.25 g of Sodium Chloride in a total of 250 cm3 of water. What is the concentration % w/v of Sodium Chloride in the solution?
Click to Remove Question
Ratio Solution
The calculation can be done using ratios:
250
100 cm3 of water contains 0.9 g of Sodium Chloride
The concentration of Sodium Chloride is therefore 0.9 % w/v.
250 cm3 of water contains 2.25 g of Sodium Chloride
Thus: 100 cm3 of water contains 100 x 2.25 g of Sodium Chloride250
100 cm3 of water contains 0.9 g of Sodium Chloride
The concentration of Sodium Chloride is therefore 0.9 % w/v.
Equation Solution
The calculation can be solved using the equation:
% w/v = mass of solute x 100 (g/100 ml)
volume of product
volume of product
% w/v = 2.25 x 100 g/100 ml
250
250
% w/v = 0.9 g/100 ml
The concentration of Sodium Chloride is 0.9 % w/v.
The concentration of Sodium Chloride is 0.9 % w/v.