How many mililiters of pure acid should be added to 35 ml. of 30% acid to make 50% acid solution?

Answer 1

.3(35 + x = .5(x+35)

x-.5x = 35(.5) - 35(.3)

.5x = 35(.2) = 7

x = 14 mL of pure acid mixed with 35 mL of 30% to get 49 mL of 50%

check the answer

.3(35) + 14 = .5(49)

10.5 +14 = 24.5

30% is within 20 of 50%

100% is within 50 of 50%

50/20 = 2.5 = 35/14

you need 2 1/2 times as much of 30% as 100%

35 is 2.5 times 14