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

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

1 Answer
Aug 17, 2016

Answer:

#"100 g"#

Explanation:

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

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

Now, your goal here is to figure out how much potassium chloride can be dissolved in #"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)|)))#