If you have 200 mL of a 60% sodium chloride solution, how much NaCl is dissolved in the solution?

Answer 1

the previous answer is succinct and correct. Let's understand this a little more.

FIRST - make sure you understand that % means "per cent", literally "out of 100".

We will assume what you are given is a weight percent.

So, 60% NaCl solution means 60 grams of NaCl are dissolved in 100 grams of solution.

Also understand that when dealing with percents in word problems, it not only means there is some number out of 100, but it helps ENORMOUSLY to put units or labels to these numbers, and KNOW that the units have to match. In this case, 60 grams/100 grams. Non-matching units is one of the biggest sources of mistakes in % word problems on the TEAS. Watch out. Contact me if you need clarity on this.

The next assumption we have to make in this problem is that the density of the solution is 1 gram/mL. After all,you are given a volume of solution, not a weight. And it doesn't make sense to say I have 60 mL of NaCl. NaCl is a salt. Assuming solutions have a density of 1 gm/mL is a common assumption.

You are given 200 mL of solution.

If 1 mL or solution weights 1 gm, then 200 mL will weigh 200 grams.

Next,

If 100 grams (or 100 mL) of solution has 60 gm of NaCl (60% solution),

then 200 grams (200 mL) of solution has 120 grams of NaCl.

----

I know that is a complex and wordy explanation. However I can't stress enough how understanding how UNITS work in math word problems helps you set up the right equation and more quickly solve the problem - with confidence.