math help
posted by amy .
A lab assistant wants to make FIVE LITERS of 31.2% acid solution. If solutions of 40% and 18% are in stock, how many liters of each must be mixed to prepare the solution.
i don't even know what equation to use or anything, please help me, thank you.

the amount of acid in a solution is the % times the volume.
For example 5L of 50% solution has 2.5L of acid.
So, if you add up all the acid in the parts of your solution, they must add up to the total acid at the end.
If x is the amount of 18% solution, then there must be 5x liters of 40% solution, since the total volume is 5 liters.
Now, adding up the amount of acid, we need
.18x + .40(5x) = .312(5)
.18x + 2  .4x = 1.56
.22x = .44
x = 2
so, 2L of 18% and 3L of 40% will produce 5L of 31.2%
.18*2 + .40*3 = .36+1.2 = 1.56 = .312*5
Respond to this Question
Similar Questions

algebra
a chemist needs 10 liters of a 25% acid solution. the solution is to be mixed from three solutions whose acid concentrations are 10% 20% 50% how may liters of each solution should the chmist use to satisfy the following? 
Algebra 2
a chemistry lab assistant wants to prepare 10 liters of 48% acid solution. in stock he has 80% and 40% acid solutions. how many liters of each in stock solution should he mix to prepare a 10liter mixture? 
Math
A chemistry teacher needs 2.5 liters of a sulfuric acid solution that is 20% sulfuric acid and 80% water . He has 2 liters of a 15% sulfuric acid solutionleft over from earlier laboratory exercises. He also has 44 liters of a 50% solution. … 
Math help please
A lab assistant wants to make five liters acid solution. If solutions of 40% and 18% are in stock, how many liters of each must be mixedto prepare the solution Amount in liters: 40%: 18%: 
Math
I need help atleast an equation to get started please A lab assisstant wants to make five liters of 27.8% acid solution. If solutions of 50% and 13% are in stock, how many liters of each must be mixed to prepare the solution. 
math
a lab assistant wants to make 5 liters of 27.8% acid solutions. if solutions of 50% and 13% are in stock, how many liters of each must be mixed to prepare the solution? 
algebra
A lab assistant wants to make 5 liters of 27.2% acid solution. If solutions of 30% and 16% are in stock, how many liters of each must be mixed to prepare the solution? 
algebra
A chemistry lab wants to prepare 300 liters of 25% acid solution. In stock he has 20% and 35% acid solutions. How many liters of each in stock mixture should he mix tp prepare a 300liter mixture? 
Algebra 2
One hundred liters of a 57.84% acid solution is obtained by mixing a 75% solution with a 42% solution. How many liters of each must be used to obtain the desired mixture? 
Algebra 2
One hundred liters of a 57.84% acid solution is obtained by mixing a 75% solution with a 42% solution. How many liters of each must be used to obtain the desired mixture?