Question

4 Pre-Lab S2 4 of 7 Review Constants Periodc Table Part A A saturated solution of manganese(i) hydroxide was prepared, and an acid-base traton was performed to determine ts K, at 25 C. The endpont was reached when 60.00 ml. of the manganese0 hydrowide soluton was terated with 3.63 mL of 0.0020 M HCI solution. What is the K., of manganese() hydroxide? Request Anawer Previous Answers Submit x Incorrect; Try Again; 3 attempts remaining Next

a saturated solution of manganese(ll) hydroxide was prepared, and an acid-base titration was performed to determine its Ksp at 25*C. the endpoint was reached when 60.00 mL of the manganese(ll) hydroxide solution was titrated with 3.63. mL of 0.0020 M HCL solution. What is the Ksp of manganese(ll) hydroxide?

Answer 1

In saturated solution, the Mg(OH)₂ remains in equilibrium with Mg²⁺ and OH^- ions.

$Mg(OH)_2(s)\rightleftharpoons Mg^{2+}(aq)+2OH^-(aq)$

So, if solubility of Mg(OH)₂ is 'S', then solubility product = K_sp = S x (2S)² = 4S³

Now, we know from condition of equivalency,

$V_{acid}\times C_{acid}=V_{base}\times C_{base}$

Here, V_acid = 3.63 mL C_acid = 0.002 M and V_base = volume of Mg(OH)₂ = 60 mL

Thus,

$C_{base}=\frac{3.63mL\times 0.002M}{60mL}=1.21 \times 10^{-4}$

Now, actual base is OH^- which has a concentration twice that of Mg²⁺ in solution. So, here,

2S = 1.21 x 10^-4

thus, S = 6.05 x10^-5

So, K_sp = 4 x (6.05 x10^-5)³ = 8.857 x 10^-13

So, this is the K_sp of Mg(OH)₂.