b) Which of these reactions are spontaneous under standard conditions? c) for ea

ID: 1021671 • Letter: B

Question

b) Which of these reactions are spontaneous under standard conditions?

c) for each of the reactions, predict the manner in which the change in free energy varies with an increase in temperature

1) Ti(s) + 2Cl2(g) ---------------------> TiCl4 (g)

Horxn = Hoproducts - Horeactants = HoTiCl4 - (HoTi +2 x HoCl2) = - 763.16 - (0 + 2 x 0) = - 763.16 kj/mol

Sorxn = Soproducts - Soreactants = SoTiCl4 - (SoTi +2 x SoCl2) = 354.80 - (30.67 + 2 x 233) = - 141.87 J/mol K

Go = Ho - T So = - 763.16 - 298 x (- 0.14187) = -720.88 kJ/mol

2) C2H6(g)+7Cl2(g) -> 2CCl4(g)+6HCl(g)

Horxn = Hoproducts - Horeactants=-682.52 kJ/mol

Sorxn = Soproducts - Soreactants= -51.28 J/mol K

Go = Ho - T So=-667.24 kJ/mol

3) BaO(s)+CO2(g)BaCO3(s)

Horxn = Hoproducts - Horeactants = ( - 1216.3 ) - (-553.5 + -393.5) = - 269.3 kJ/mol

Sorxn = Soproducts - Soreactants = 112.1 - (70.4 + 213.6) = - 171.9 J/mol K

Go = Ho - T So = - 269.3 - 298 x (- 171.9 x 10^-3) = - 218 kJ/mol

1) Ti(s) + 2Cl2(g) ---------------------> TiCl4 (g)

delta G = negative

So the reaction is spontaneous

delta G = delta H - T*delta S

delta H is negative but delta S is positive

So increasing temperature will take delta G more negative

2) C2H6(g)+7Cl2(g) -> 2CCl4(g)+6HCl(g)

delta G = negative

So the reaction is spontaneous

delta G = delta H - T*delta S

delta S is negative and delta H is negative

So increasing temperature will take delta G less negative and increasing temperature further willl make delta G positive

3) BaO(s)+CO2(g)BaCO3(s)

delta G = negative

So the reaction is spontaneous

delta G = delta H - T*delta S

delta S is negative and delta H is negative

So increasing temperature will take delta G less negative and increasing temperature further willl make delta G positive

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