A pot contains 3 L of brine at a concentration of 110 g/L. How much of the water should be boiled off to increase the concentration to 220 g/L?

Question

need help finding how much water is needed

Answer 1

Hi Alexa,

 

We can first read through the problem to logically identify how to set it up. We are given L of bring and g / L, then another g / L, so we need to find the missing L (Understand? Comment if you don't.). But we need to keep in mind that the first L was given for brine, while the second L is for water.

 

So, here's our equation:

 

x is the amount of water needed to be boiled off.

 

3 L * (110 g / L) = (3 - x) * (220 g / L)

 

I multiplied them together because L * (g / L) gives me units of g, which is equal on both sides, which is necessary for an equation, to have two sides that are equal to one another.

 

Now we solve!

 

330 = 660 - 220x

 

3 = 6 - 2x (divide both sides by 110)

 

x = 1.5 L

 

Hope this helps!