Modelling Linear Systems, using Volume, Percentage and mL

Question

What volume, in millilitres, of 60% hydrochloric Acid sol. must be added to a 100mL of a 30% hyrdrochloric acid sol. to make a 36% hyrdrochloric acid sol.?

Answer 1

Let V be the required volume of hydrchloric acid solution.

 

The new volume will be 100 + V and the total amount of HCL in the solution is 36% (100 + V) = 36 + 0.36V

The amount of HCL in 100 mL at 30% =  30% * 100 = 30.   

The amount of HCL in V ml of 60%  = 60% * v = 0.6V

 

36 + 0.36V = 30 + 0.6V

 

6 = 0.24V   v = 6/.24 = 25 mL