Question

4) For which of the folling pure chemical substances will sº = 0.0 J/mol.K when T = 25.0°C? a) FeCl(s) b) O2(g) c) O3(g) d) Both b and c e) None of the above b) AS 5) For a particular chemical reaction it is found that the value for the equilibrium constant for the reaction decreases as temperature increases. Based on this we can conclude a) AS rxn <0 0 c) AHºrx<0 d) AHºrx>0 <0 e) AGºran

Answer 1

4)so, the correct answer is e) none of the above.

If we talk about the value of entropy at standard conditions(S^o) at 25^oC,

for FeCl₃(s)= 142.3J/K-mol,

O₂(g)= 205.0 J/K-mol

O₃(g)= 238.9J/K-mol

5) The value of equilibrium constant depends on temperature.

For exothermic reaction,

when the temperature increases , the value of equilibrium constant decreases.

this is because

we have the relation,

Kc= [product]^a/[reactant]^b

where a, b are the the co-efficients of product and reactant respectively,

lets assume the reaction mentioned below

A+B$\rightleftharpoons$ AB

let this reaction be exothermic in forward direction

if we increase the temperature then according to Lechatelier's principle the equilibrium will move backward that would decrease the value of of equilibrium constant

so, the correct option is c)$\Delta$H_rxn<0 i.e. negative(exothemic reaction)

i hope this helps you..