How can I calculate solubility of potassium nitrate?

Question

Natalie Anton · Accepted Answer

The only way to determine the solubility of potassium nitrate is to do an experiment or interpolate from a solubility graph.

Solubility is the mass of a solute that can be dissolved in a given mass of solvent.

Solubility varies according to temperature for the same solute and solvent.

The solubility graph for potassium nitrate in water is shown below.

EXAMPLE

What is the solubility of potassium nitrate at 50 °C?

Solution

Read along the horizontal axis until you reach 50 °C. From there, extend a line upwards until it meets the graph.

Then extend a horizontal line to the vertical axis. Read the temperature at that point.

The solubility is about 90 g of KNO₃ per 100 g of water.

Cooper Adams · Answer

undefined The solubility of potassium nitrate can be calculated using its solubility product constant (Ksp) and the concentrations of its ions in solution. The equation for the solubility product constant of potassium nitrate (KNO3) is:

Ksp = [K⁺][NO3⁻]

To find the solubility (S) of potassium nitrate, you can use the molar solubility (x) and the balanced equation for its dissociation:

KNO3(s) ⇌ K⁺(aq) + NO3⁻(aq)

Then, you can set up an equilibrium expression for the dissociation of potassium nitrate and use it to solve for the molar solubility (x).