# What is the total mass of #KNO_3# that must be dissolved in 50 grams of #H_2O# at 60°C to make a saturated solution?

##### 1 Answer

#### Explanation:

In order to solve this problem, you must take a look at the **solubility graph** for *potassium nitrate*,

Now, the solubility graph shows you how much solute can be dissolved **per** *unsaturated*, a *saturated*, or a *supersaturated* solution.

You're looking to make a **saturated** potassium nitrate solution using

As you can see, the curve itself represents saturation.

If you draw a *vertical line* that corresponds to *horizontal line* that connects to the vertical axis, you will find that potassium has a solubility of about **per**

Use this as a **conversion factor** to help you find how much potassium nitrate can be dissolved in

#50color(red)(cancel(color(black)("g water"))) * overbrace("115 g KNO"_3/(100color(red)(cancel(color(black)("g water")))))^(color(purple)("solubility at"color(white)(a) 60^@"C")) = "57.5 g KNO"_3#

You *should* round this off to one **sig fig**, since that's how many sig figs you have for the mass of water, but I'll leave it rounded to two sig figs, just for good measure

#m_(KNO_3) = color(green)(|bar(ul(color(white)(a/a)"58 g"color(white)(a/a)|)))#