Question

1. Find [Hg2+] in saturated Hg2Br2 in 0.001M KBr.

2. Using activities, calculate the pH of a solution containing 0.010M NaOH plus 0.012M LiNO3. What would be the pH if you neglected activities?

3. For 0.1M aqueous solution of sodium acetatae, Na+CH3CO2-, one mass balance is simply [Na+]=0.1M. Write a mass balance involving acetate.

4. Write a mass balance for a solution of Fe(SO4)3

Answer 1

1) 0.001 M KBr is the defined solution

log(γ) = -0.509 * ( 1 + 1) * √(0.001) = -3.22E-2

γ = 0.9683

[Hg2+] = 0.5 * [Br-] * γ = 0.5 * 0.001 * 0.9683 = 4.8416E-4 M

2) NaOH is a strong base so it will be completely dissociate as well it determine the would acidity of the mixture.

NaOH ---> (Na+) + [OH-]

[OH-] = 0.010 M

pOH = -log [OH-]

= -log[1E-2 M]

= 2

pOH + pH = 14

pH = 14 - 2

pH = 12

3) CH3COO-C2H5 + NaOH <===> CH3COO-Na+ + C2H5OH

ethyl acetate + sodium hidroxilum - sodium acetate + ethanol.

4) Fe2(SO4)3 <---> 2Fe3+ + 3SO4-

3[Fe3+] + 3[Fe(OH)--] + 3[Fe(OH)2-) + 6[Fe2(OH)2++++] + 3[FeSO4+] = 2[FeSO4+] + 2[SO4--] + 2[HSO4-]