# Concentration of Solutions_ Mass_Mass % (m_m)%

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Concentration of a mass/mass percent. A mass/mass percent
gives the mass of a solute divided by the mass of a
solution (expressed as a percent) - referred to as percent (m/m)
So here's the equation,
mass/mass percent = mass of solute in grams (g)
divided by the mass of the solution also in grams. So
mass/mass percent (m/m)%
And then we'll multiply the final by 100 to give us our percent.
Let's look at a sample problem.
Calcium chloride is used to melt ice on the road. To determine how much calcium
chloride has been used, you take sample of slush to analyze it.
And that sample of slush with calcium chloride is 23.47 grams.
When the solution was evaporated, and the residue we're going to have left behind
and we're going to assume it as a pure solute, we're going to assume it was only ice water and calcium chloride.
So, the residue I'm going to have left behind is 4.58 grams.
What was the mass/mass percent of calcium chloride in the slush?
And then how many grams pf calcium chloride were present in 100 grams of solution?
So to start out with our equation
so mass/mass percent is equal to the mass of solute in grams
divided by the mass of solution.
So we're dissolving into a solvent to get our final solution and then multiply it by 100
So what information are we given?
So, what was the mass of the solute? Well that's the residue that's left behind - 4.58 grams.
Mass of the solution - 23.47 grams. We're going to multiply that
Then when we divide them by 100,
and we're going to get 19.5 percent
mass/mass. But now 19.5 percent so that answers
this part of the question. Then it asks, how many grams
of calcium chloride, so all it is, is
get rid of this percent and rewrite it as
19.5 - but instead of percent - it's 19.5 of
what? The mass, which is grams - divided by
what is the overall mass of our solution, and we're always going to refer it to
100 and 100 if we're looking at mass the mass unit have to be in grams.
So the answer in mass/mass percent is 19.5 percent.
But it turns up a odd like how much of this was present in 100 grams of the solution
well it's 19.5 grams of it is going to be
dissolved in 100 grams in our entire solution.