00:01
Because we have such an incredibly small ksp value for calcium phosphate, ca3, po42, then if we were to add 8 .5 grams to 50 milliliters of water, we're definitely going to saturate the solution.
00:21
Calcium phosphate will separate into three calcium ions and two phosphate anions.
00:29
So ksp is simply equal to the calcium concentration.
00:36
Cubed, multiplied by the phosphate concentration, squared, and that numerical value is provided at 2 .07 times 10 to the negative 33.
00:52
So the amount of calcium phosphate that we added per volume really is not important.
00:57
It's just the fact that we have a saturated solution.
01:02
If we have a saturated solution, then we're going to get three calciums every time one of the solid dissolves in a liter, we'll get three, if one mole of the solid dissolves in a liter, we'll get three moles of calcium per liter.
01:20
So that means the calcium concentration is equal to three times the molar solubility of the solid that i'll call s, and the phosphate concentration is equal to two times the molar solubility.
01:35
Every time one mole of the solid dissolves in a liter, we get two moles of phosphate per liter.
01:41
So knowing this, we can go back to our ksp expression and our ksp value.
01:49
We'll plug in 3s for calcium and plug in 2s for phosphate.
01:56
3s cubed, multiplied by 2s squared, equals 2 .07 times 10 to the negative 33.
02:11
So 3 cubed is 27, 2 squared is 4, 4 times 27 is 108, and then we'll we've got s to the fifth is equal to 2 .07 times 10 to the negative 33.
02:28
So s is going to be equal to 2 .07 times 10 to the negative 33 divided by 108 raised to the one -fifth.
02:43
And we get 1 .14 times 10 to the negative 7 molar...