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1. Determine the pH of each of the following solutions a) 0.095 M hypochlorous a

ID: 854004 • Letter: 1

Question

1. Determine the pH of each of the following solutions a) 0.095 M hypochlorous acid b) 0.0085 M hydrazine, c) 0.165 M hydroxylamine

hypochlorous acid HClO 3.0 x 10-8 = Ka1

3)The activation energy for the isomerization of methyl isonitrile is 160 kJ/mol. Calculate the fraction of methyl isonitrile molecules that has an energy of 160.0 kJ or greater at 500 K. b) Calculate this fraction for a temperature of 520K. What is the ratio of the fraction at 520 K to that at 500 K?

1. Determine the pH of each of the following solutions a) 0.095 M hypochlorous acid b) 0.0085 M hydrazine, c) 0.165 M hydroxylamine hypochlorous acid HClO 3.0 x 10^-8 = Ka1 2) Phosphorus trichloride gas and chlorine gas react to form phosphorus pentachloride gas: PCl3(g) + Cl2(g) PCl5(g). A 7.5 L gas vessel is charged with a mixture of PCl3(g) and Cl2(g), which is allowed to equilibriate at 450K. At equilibrium the partial pressures of the three gases are PPCl3=0.124 atm, PCl2=0.157 atm, and PCl5=1.30 atm. a) Calculate Kc for this reaction? 3)The activation energy for the isomerization of methyl isonitrile is 160 kJ/mol. Calculate the fraction of methyl isonitrile molecules that has an energy of 160.0 kJ or greater at 500 K. b) Calculate this fraction for a temperature of 520K. What is the ratio of the fraction at 520 K to that at 500 K?

Explanation / Answer

(a)
HClO <-- --> H+ + ClO-
0.125______0____0_
0.125-X____X____X_

Ka = X^2 / (0.125-X) =
= 3*10^-8 ? X^2 / 0.125

X = [H+] = (0.125*3*10^-8)^1/2 = 6.12*10^-5 M

pH = -Log(6.12*10^-5) = 4.21

(b)
Ph-OH +H2O <-- --> PhOH2+ + OH-
0.0085____________0_______0_
0.0085-X__________X_______X_

Kb = 10^-14 / Ka = X^2 / (0.0085-X) =
= 7.7*10^-5 ? X^2 / 0.0085

X = [OH-] = (0.0085*7.7*10^-5)^1/2 = 8.08*10^-4 M
then
pOH = -log(8.08*10^-4) = 3.09

pH = 14 - 3.09 = 10.91

(c)...similarly