Hi, I have 2 separate questions that I am not too sure how to answer.
The first one is related to entropy:
1) Nitrogen(III) oxide, N2O3, an air pollutant, dissolves in rainwater to form a dilute solution of nitrous acid. The equation for the reaction is: N2O3(g) + H2O(l) → 2HNO2(aq)
Calculate ΔS° for this reaction in J mol-1 K-1. Use data in the table below:
Compound | S °, (J mol-1 K-1)
N2O3(g) | 307
H2O(l) | 69.96
HNO2(aq) | 135.6
I thought that:
ΔS° = sum(S ° products) - sum(S ° reactants)
= 135.6 - (307 + 69.96)
= -241.36 J mol-1 K-1
But, this was a wrong answer. Where did I go wrong?
The second question is related to solubility.
2)
a) When 25.0 mL of a solution of 1.4 x 10-3 M silver nitrate is mixed with 60.0 mL of a solution of 7.5 x 10-4 M sodium chloride, what is the molar concentration of silver ions in the final mixture?
b) What is the molar concentration of chloride ions in the final mixture?
Based on a comparison between Qsp and Ksp for this mixing reaction, a precipitate of silver chloride
will/will not(?) form. (Ksp (AgCl) = 1.8 x 10-10)
With this one, I calculated n(AgNO3) to be 3.5x10^-5 mol, and n(NaCl) to be 4.5x10^-5mol, but I do not know what to do next? I thought that the number of moles of each should be the same because of the molar ratios in the equation, so I'm lost.
Thank you for your help.