Question

help with 35

Use the following table for questions 33-36. Substance Ca(OH)2(s) H&ASO4(aq) Ca(H2ASO4)2(aq) H2O(1) AHt (kJ/mol) Substance AHO (kJ/mol) -46.19 +90.37 NH (g) NOg) C.H:(g) C2H&(g) -986.6 900.4 -2346.0 +226.78 -285.9 -84.68 33 Given the data in the table below, AHo for the following reaction is Ca(OH) (s)+2HASO4(aq)Ca(H2ASO4)2 (aq) +2H20(1) kJ. A) 4219 -130.4 C) D) 451 -76.4 Calculate AHr for 4 NH (g)+5 O2(g)4 NO(g) +6 H2O() 34. -1172 kJ A) +1172 kJ C) D) B) 1539 kJ -241.7 kJ 35 Using standard enthalpies of formation, calculate the heat of hydrogenation of acetylene gas, C2H2(g), to form ethane gas CaH:(g)+2H2(g)CaHalg) A) B) C) D) -32.3 kJ -307.4 kJ +32.3 kJ +307.4 kJ

Answer 1

35)

Given:

Hof(C2H2(g)) = 226.78 KJ/mol

Hof(H2(g)) = 0.0 KJ/mol

Hof(C2H6(g)) = -84.68 KJ/mol

Balanced chemical equation is:

C2H2(g) + 2 H2(g) ---> C2H6(g)

ΔHo rxn = 1*Hof(C2H6(g)) - 1*Hof( C2H2(g)) - 2*Hof(H2(g))

ΔHo rxn = 1*(-84.68) - 1*(226.78) - 2*(0.0)

ΔHo rxn = -311.46 KJ

Option B is closest

Answer: B