00:01
So our ksp reaction as represented is croh3 solid dissociating into cr3 +, plus 3oh-, and at a ph of 11 .9 we can calculate the hydroxide concentration.
00:25
The hydroxide concentration will be equal to kw, 1 .0 x 10 to the negative 14, divided by the hydronium concentration, which is 10 to the negative ph, the ph of 11 .9, and we get a hydroxide concentration of 7 .94 x 10 to the negative 3.
00:51
So going back to our ksp expression, the solid won't really have a change in concentration, so this will be negligible, but we'll have an initial concentration of cr0, and hydroxide of 7 .94 x 10 to the negative 3.
01:17
So it should be positive rather than negative in your ice table, this value.
01:26
Then we're going to have it shift to the right, this will increase by x and this will increase by 3x, so we'll have x at equilibrium and 7 .94 x 10 to the negative 3 plus 3x, but typically we make the assumption that that increase of 3x is going to be negligible in comparison to the original concentration of 7 .94 x 10 to the negative 3.
01:59
Ksp is then going to be equal to cr3 plus concentration, multiplied by the hydroxide concentration cubed, and to calculate molar solubility, we recognize that the concentration of the chromium will be equal to molar solubility, because when one mole of the solid dissolves in a liter, we'll get one mole of chromium ion in a liter...