What is the maximum amount of "KCl"KCl that can dissolve in 300 g of water at 20°C?

The solubility of "KCl"KCl is 34 g/100 g "H"_2"O"H2O at 20°C.

1 Answer
Stefan V.
Aug 17, 2016

"100 g"100 g

Explanation:

The problem provides you with the solubility of potassium chloride, "KCl"KCl, in water at 20^@"C"20∘C, which is said to be equal to "34 g / 100 g H"_2"O"34 g / 100 g H2O.

This means that at 20^@"C"20∘C, a saturated solution of potassium chloride will contain "34 g"34 g of dissolved salt for every "100 g"100 g of water.

As you know, a saturated solution is a solution that holds the maximum amount of dissolved salt. Adding more solid to a saturated solution will cause the solid to remain undissolved.

In your case, you can create a saturated solution of potassium chloride by dissolving "34 g"34 g of salt in "100 g"100 g of water at 20^@"C"20∘C.

Now, your goal here is to figure out how much potassium chloride can be dissolved in "300 g"300 g of water at this temperature. To do that, use the given solubility as a conversion factor to take you from grams of salt to grams of water

300 color(red)(cancel(color(black)("g H"_2"O"))) * "34 g KCl"/(100color(red)(cancel(color(black)("g H"_2"O")))) = "102 g KCl"

You should round this off to one sig fig, since that is how many sig figs you have for the mass of water

color(green)(|bar(ul(color(white)(a/a)color(black)("mass of KCl " = " 100 g")color(white)(a/a)|)))

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