Calculate δg o for each reaction using δg of values: (a) h2 (g) + i2 (s) → 2hi (g) kj (b) mno2 (s) + 2co (g) → mn (s) + 2co2 (g) kj (c) nh4cl (s) → nh3 (g) + hcl (g)

Part (a):

H₂ (g) + I₂ (s) → 2 HI (g)

From given table:

G HI = + 1.3 kJ/mol

G H₂ = 0

G I₂ = 0

ΔG = G (products) - G (reactants) = 2 (1.3) = 2.6 kJ/mol

Part (b):

MnO₂ (s) + 2 CO (g) → Mn (s) + 2 CO₂ (g)

G MnO₂ = - 465.2

G CO = - 137.16

G CO₂ = - 394.39

G Mn = 0

ΔG = G (products) - G (reactants) = (1 (0) + 2*-394.39) - (-465.2 + 2*-137.16) = - 49.3 kJ/mol

Part (c):

NH₄Cl (s) → NH₃ (g) + HCl (g)

ΔG = ΔH - T ΔS

ΔG = (H (products) - H (reactants)) - 298 * (S (products) - S (reactants))

= (-92.31 - 45.94) - (-314.4) - (298 k) * (192.3 + 186.8 - 94.6) J/K

= 176.15 kJ - 84.78 kJ = 91.38 kJ