Doreen schmidt is a chemist. She needs to prepare 36 ounces of a 10% shydrochloric acid solution. Find the amount of 18% solution and the amount of 9% solution she should mix to get this solution

Total = 36oz

Amount of 18% solution = x

Amount of 9% solution = 36 - x

Using the fact that (amount of solution) * (percent HCl) = amount HCl we can set up an expression for the amount HCl in a mixture of 18% and 9% solutions with a total volume of 36oz.

Amount of HCl = x*0.18 + (36 - x) * 0.09

If we divide this by the amount of solution we get percent HCl, and we have a target of 10% HCl. Now we have an equation to solve,

[x*0.18 + (36 - x) * 0.09]/36 = 0.1

x*0.09 + 3.24 = 3.6

.09x = 0.36

x = 4

Therefore,

4 ounces of 18% HCl solution and 32 ounces of 9% HCl solution

Check:

[ (4*.18) + (.09*32) ]/36 = 0.1?

0.1 = 0.1 Yes.