Question

4 Look at the decomposition reaction for Marks: 2 sodium bicarbonate. 2NaHCO3(s) Na2CO3(s) + H2O(g) + CO2(g) Suppose that triangle H = 64.5 kJ/mol and triangleS = 0.167kJ/mol.K. Which statement about this reaction is correct? Assume that triangleH and triangleS are constant for all the given temperatures. Choose one answer a. The reaction is spontaneous at 327 K. b. The reaction is spontaneous at 380 K. c. The reaction is at equilibrium at about 386 K. d. The reaction is nonspontaneous at 427 K.

Answer 1

Solution :-

Delta H= 64.5 kJ / mol

Delta S = 0.167 kJ /mol .K

Using the delta H and delta S values lets calculate the temperature above which reaction can become the spontaneous

For the spontaneous reaction the value of the delta G need to be less than zero

here lets assume delta G = 0

Delta G = Delta H - T*Delta S

delta G = 0

therefore we get the following equation

T= Delta H / Delta S

T = 64.5 kJ per mol / 0.167 kJ per mol. K

T = 386 K

Therefore Reaction will be at equilibrium at 386 K

Therefore the statement in the option C is the correct statement.