Calculating Ksp of Magnesium Carbonate

The solubility of Magnesium Carbonate in water is 0.39 grams per liter. The question is, what is the Ksp of MgCO3?

Transcript

00:00The solubility of magnesium carbonate in water is 0.39 grams per liter.

00:07The question is, what is the Ksp of MgCO3?

00:13Okay, the first step is identification.

00:19The solubility of magnesium carbonate is 0.39 grams per liter.

00:25The relative molecular mass of magnesium carbonate is 24.3, plus 12, plus 3 times 16.

00:36That is 84.3 grams per mole.

00:40The next step is to calculate the molar solubility.

00:45Solubility is equal to Mr times the molar solubility.

00:48Plug in the solubility and relative molecular mass.

00:52The molar solubility is equal to 4.626 times 10 to the power of negative 3 moles per liter.

01:00The third step is to analyze the ionic equilibrium.

01:05In water, a molecule of magnesium carbonate ionizes into a Mg2 plus ion and a carbonate

01:11ion.

01:13The solubility value is measured when the solution is exactly saturated or supersaturated.

01:19In this condition, the magnesium carbonate molecules and their ions form a chemical equilibrium.

01:28And in 1 liter of water.

01:31So in this solution, there are 4.626 times 10 to the power of negative 344 moles of Mg2

01:38plus ions.

01:41And 4.626 times 10 to the power of negative 3 moles of carbonate ions.

01:49So the molarity of magnesium ions is 4.626 times 10 to the power of negative 3 molar.

01:58While the molarity of carbonate ions is 4.626 times 10 to the power of negative 3 molar.

02:06The fourth stage is to write the chemical equilibrium equation.

02:11This chemical equilibrium equation is very difficult to read.

02:15Let's just look at the monitor screen.

02:19Now we can calculate Ksp.

02:22Ksp is equal to the concentration of magnesium ions, multiplied by the concentration of carbonate

02:28ions.

02:30Enter the ion concentration value.

02:33The result of the calculation is 2.14 times 10 to the power of negative 5.

02:39This is the Ksp of magnesium carbonate.

02:44Yup, hopefully useful.

02:46And don't forget to follow this channel.