Question
Answer in KJ/MOL
2CIF3(g) + 2NH3(g) rightarrow N2(g) + 6HF(g) + Cl2(g) and that delta H degree f HF(g) = -271.0 kJ/mol and delta Hof NH3(g) = -46.00 kJ/mol While attempting this problem, a student incorrectly reads the table of delta H degree rxn, values provided and uses -1244 kJ for delta H degree rxn. He then correctly performs the algebra required to solve this problem, but gets the question wrong due to the fact that he used the incorrect delta Horxn in his calculations. What value of delta H degree f CIF3(g) did the student calculate' Calculate your answer to the correct number of significant figures. kJ/mol
Explanation / Answer
H(reaction) = Ho(reaction) - [ 6*H(HF) - 2H(ClF3) - 2H(NH3) ]
Ho = [ 6*H(HF) - 2H(ClF3) - 2H(NH3) ]
-1244 = 6*(-271) - 2(ClF3) - 2(-46)
-1244 + 1626 - 92 = -2H(ClF3)
H(ClF3) = -145 KJ/mol.