<p>One liter of saturated zinc hydroxide solution contains 0.000222 g of dissolved Zn(OH)2. Calculate Ksp for Zn(OH)2.</p>
<p>(a) 4.8 x 1012 (b) 2.6 x 1016 (c) 4.5 x 1017
(d) 7.1 x 1014 (e) 1.1 x 1017</p>
<p>What is the answer and explanation? Thanks.</p>
<p>Net ionic equation:
Zn(OH)2 (s) → Zn2+(aq) + 2OH-(aq)</p>
<p>We need to find the concentration of the products so:
0.000222g Zn(OH)2 / 99.406g/mol = 2.23*10^-6mol Zn(OH)2</p>
<p>2.23<em>10^-6 mol Zn(OH)2 * (1mol/1mol) = 2.23</em>10^-6 mol Zn2+</p>
<p>2.23<em>10^-6 mol Zn(OH)2 * (2mol/1mol) = 4.47</em>10^-6 mol OH-</p>
<p>Since there is 1L of solution, the concentrations are:
[Zn2+] = 2.23<em>10^-6 mol/L
[OH-] = 4.47</em>10^-6 mol/L</p>
<p>Ksp is an equilibrium constant so the formula is as follows:</p>
<p>concentration of product^coefficient / concentration of reactants^coefficient</p>
<p>Since Ksp relates to solubility, the solid products or reactants are ignored.</p>
<p>so: [Zn2+]*[OH-]^2 = Ksp ([OH-] is squared because its coefficient in the net ionic equation is 2)</p>
<p>(2.23<em>10^-6) * (4.67</em>10^-6)^2 = Ksp</p>
<p>Ksp = 4.45*10^-17 </p>
<p>The answer is C</p>
<p>Make sure you check your algebra with the exponents</p>