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Question

Question #1 

4.86 g of Ag₂SO₄ will dissolve in 1 l of water. Calculate the solubility product constant for this salt 

 

Question #2

H₂  and Cl₂  combine to for HCl. In a gas phase equilibrium mixture of H₂, Cl₂ and HCl at 1000 K, [HCl]= 0.0032 mol/L and [Cl₂] = 0.002 mol/L. Calculate the concentration of H_2. K_c = 5.1 x 10-8 at this temperature. Answer in units of mol/L. 

Answer 1

part 1   the equation for this equilibrium is Ag₂SO₄ ⇔ 2Ag⁺ + SO4^-

the atomic weight of silver sulfate is 2Ag (107.86) + S (32.06) + O(16•4) = 311.78

 

we have 4.86g = 4.86/311.76 = 0.0156 mols

the concentration of Ag⁺ = 2(0.0156) = 0.0312mols, and SO4^- = 0.0156

 

so, the solubility constant is K_sp = [Ag+]²[SO4-]

 

we get K_sp = [0.0312]²[0.0156] = 0.000974•0.0156

K_sp = 0.0000151 = 1.51x10^-5

 

part 2  According to text I have entitled the "Principles of Chemistry", there is generally no good way to predict how the solubility will vary with temperature.

If your text or teacher has a different view, I will be interested to know what it is.