advanced chemistry?

Question

Give the equation for Kp for the reaction:

N2(g) + 3H2(g) F 2NH3(g)

ii) In an equilibrium mixture the partial pressure of N2 was 0.305 atm while that of hydrogen was 0.324 atm. If Kp = 61.1 calculate the equilibrium pressure of NH3 and the total pressure of the mixture.
iii) Will the equilibrium composition shift towards reactants or products, or remain the same, if the total pressure is doubled?

4) When 0.515 g of liquid methanol, (CH3OH, molar mass = 32) was burned in oxygen in a bomb calorimeter the temperature of the calorimeter increased from 25 to 26.06 oC. When 2780 J of electrical energy was used to heat the calorimeter at 25 oC the temperature rose by 0.5 oC.
i) Give a balanced equation for combustion of one mole of methanol in oxygen.
ii) Calculate ∆U for this reaction.
iii) Calculate ∆Ho for this reaction at 25 oC.

[R= 8.314 J K-1 mol-1; 0 oC = 273 K]

Answer 1

This is a hard question to answer because it can't be hand written here, but I'll give it a go.

ii)
^3 means cubed
^2 mean squared

the Kp equation is Kp = ((pNH3)^2)/((pN2) x (pH2)^3)

so 61.1 = ((pNH3)^2)/(0.305 x 0.324^3)

(pNH3)^2 = 61.1 x 0.305 x 0.324^3
= 0.634

pNH3 = 0.796 (which I believe is the equilibrium pressure of NH3, but I'm not positive)

total pressure = pNH3 + pN2 + pH2

total pressure = 0.796 + 0.305 + 0.324
= 1.43 atm

iii)
If the pressure is increased more products will be formed because the equilibrium will adjust to decrease the pressure. There are 4 moles of reactants and 2 moles of products, 4 moles of gas take up more space than 2 moles, more NH3 is formed (Le Chatelier's principle).

4)
i)
CH3OH + (3/2)O2 > CO2 + 2H2O

ii)
∆U = (specific heat capacity of calorimeter, c) x ∆T

Now I think that c will be 5.56 Kj K-1 g-1, form 2 x 2780 j. But I'm not sure. I think that the mass of the calorimeter is needed.

∆U = 5.56 x 274.06
= 1523.8 Kj

moles of CH3OH = 0.0161

convert ∆U into Kj mol-1

∆U = 1523.8/0.0161 = 94646 Kj mol-1

iii)
∆H = ∆U x nRT

∆H = 94646 x 0.0161 x 0.008314 x 298
= 3775 kj mol-1

Hope this helps

Answer 2

You really should learn how to do your own Homework ..

What if the answers you get here are wrong ?

How you going check if you don't understand ??