If the molar solubility of MnCO_3 is 8. 4 times 10^-6 M at a certain temperature
ID: 498496 • Letter: I
Question
If the molar solubility of MnCO_3 is 8. 4 times 10^-6 M at a certain temperature, what is the K_sp for the compound? (Enter your answer in scientific notation.) What is the pH of a saturated solution of Zn(OH)_2? K_sp = 1.8 times 10^-14 The pH of a saturated solution of a metal hydroxide MOH is 9.10. Calculate the K_sp for this compound. Enter your answer in scientific notation. Write the balanced equation and solubility product expression for the solubility equilibrium of Mn_3(PO_4)_2: Include physical states and use correct subscripts and superscripts. K_sp expression: K_sp =Explanation / Answer
1)
MnCO3 <---> Mn2+ + CO32-
s s
Ksp = [Mn2+][CO32-]
Ksp = s*s
=s^2
= (8.4*10^-6)^2
=7.1*10^-11
Answer: 7.1*10^-11
2)
Zn(OH)2 <----> Zn2+ + 2OH-
s 2s
Ksp = [Zn2+][OH-]^2
Ksp = s*(2s)^2
Ksp = s*4*s^2
1.8*10^-14 = 4*s^3
s = 1.65*10^-5
so,
[OH-] = 2s = 2*(1.65*10^-5) = 3.30*10^-5 M
pOH = -log [OH-]
= -log(3.30*10^-5)
=4.48
pH = 14 - pOH
= 14 - 4.48
= 9.52
Answer: 9.52
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