measurement

Question

How many centiliters of pure acid must be added to 6 centiliters of a 50% acid solution to obtain a 70% acid solution?

Answer 1

Look at the acid concentrations.

6 cl of 50% acid has 6(0.5) cl of acid

To this we add x cl of acid

To obtain (x+6)cl of 70% acid or 0.7(x+6)cl acid

 

x + 6(0.5) = (x+6)(0.7)

x + 3 = 0.7x + 4.2

0.3x + 3 = 4.2

0.3x = 1.2

x = 1.2/0.3

x = 4 cl of pure acid

Answer 2

a + 0.5(6) = 0.7(a + 6)

a + 3 = 0.7a + 4.2

0.3a = 1.2

a = 4