Question

You are working as a clinical chemist in charge of the testing of blood samples. You are required to mix a solution of sodium chloride with water in the ratio of 2:5. Starting with 780ml of the sodium chloride solution, how much water needs to be added? Give your answer in standard form to an appropriate number of significant figures.

Answer 1

1,950 ml of water should be added to 780 ml of sodium chloride to maintain the ratio of 2:5

Given:
Ratio of sodium chloride to water 2:5
sodium chloride = 780 ml
water = ?

proportionality a:b = c:d where ad = bc

a = 2 ; b = 5 ; c = 780 ml ; d = x

2:5 = 780:x
2x = 780*5
2x = 3900
x = 3900/2
x = 1950 ml of water.