Question

Write the expression of solubility product of calcium phosphate in terms of its molar solublity

Answer 1

The solubility product, by definition, is the equilibrium constant for dissolution of a solid ionic compound to yield ions in solution (usually water). It is abbreviated Ksp.

The equation for dissolution of calcium phosphate (Ca3(PO4)2) in water is:

Ca3(PO4)2 = 3 Ca(2+) + 2 PO4(3-)

and the equilibrium constant will be equal to:

Ksp = [Ca(2+)]^3 * [PO4(3-)]^2

Now, if you want to solve problems like how much calcium phosphate will dissolve in water you need to replace [Ca(2+)] and [PO4(3-)] with something more useful. For every mole of Ca3(PO4)2 (set = to x), when it dissolves, will yield 3 moles of Ca(2+) (=3x) and 2 moles of PO4(3-) (=2x) so the Ksp expression becomes:

Ksp = [Ca(2+)]^3 * [PO4(3-)]^2 => (3x)^3 * (2x)^2 = 108x^5

Answer 2

Answer:

At a particular temperature, a 2.00Lflask at equilibrium contains 2.80×10−4 moles of N2, 2.5×10−5mole of O2and 2.00×10−2 mole of N2O. Calculate K at this temperature for the reaction, 2N2(g)+O2(g)→2N2O(g)

If [N2]=2×10−4M, [N2O]=0.200M and [O2]=0.00245M, does this represent a system at equilibrium.