A Scientist wants to dilute a 60% acid solution by adding some 20% solution. If she starts with 80ml of 60% solution, how many milliliters of the 20% solution does she need to add to get a resulting 45% acid solution?

Question

miracrown · Answer

did you have any ideas on starting this?  :}

miracrown · Answer

did your teacher go over any formulas like M1V1 = M2V2?

anonymous · Answer

I can't even remember where to start :(

miracrown · Answer

okay, what about did your teacher go over percents by volume?

miracrown · Answer

lets determine how many mL of the desired compound we have in 80 mL of 60% solution?
60% is 60 mL/100mL total

miracrown · Answer

so we can use that as a conversion factor
to change the mL total solution to the mL of acid
which gives us how many mL of the acid?

anonymous · Answer

ok that worked :)

miracrown · Answer

great :]

anonymous · Answer

ok so now where should I start?

miracrown · Answer

if you review what I've wrote above, you'll have a basic idea!

anonymous · Answer

45ml?

miracrown · Answer

.45*total volume

anonymous · Answer

but she started off with 80ml total volume?

miracrown · Answer

O.O... hold on.

anonymous · Answer

x = 20% acid solution

0.60(80) + 0.20x = 0.45(80 + x)

solve for x

miracrown · Answer

http://postimg.org/image/w2j6ppyxp/

anonymous · Answer

Sourwing has it right.  Use algebra.