Which of the following statements are FALSE, given the following bond dissociati

Question

Which of the following statements are FALSE, given the following bond dissociation energies? Assume that bond energies accurately determine heats of reaction. Several choices possible. BE[H-H] = 436.4 kJ/mol BE[H-N] = 393 kJ/mol BE[H-O] = 460 kJ/mol BE[O=O] = 498.7 kJ/mol Check all that are false. Question 4 options:

1.H°f[O(g)] = 498.7 kJ/mol

2.An H-H bond is stronger than an H-N bond.

3.H°f[H2O(g)] = -234 kJ/mol

4.H°[NH3(g) ---> N(g) + 3 H(g)] = 1179 kJ/mol

5.NH3(g) + HO(g) ---> NH2(g) + H2O(g) is an endothermic reaction.

Explanation / Answer

1.H°f[O(g)] = 498.7 kJ/mol ... Since this is for the O=O bond

2.An H-H bond is stronger than an H-N bond. The numerical value of H-H bond is greater than that of N-H

3.H°f[H2O(g)] = -234 kJ/mol. TRUE, it comes from th eclaculation of 2H2 + O2 --> 2H2O

4.H°[NH3(g) ---> N(g) + 3 H(g)] = FALSE, NH3 comes from N2 and H2

5.NH3(g) + HO(g) ---> NH2(g) + H2O(g) is an endothermic reaction.

Hrxn = 2*393 + 2*460 - (3*393 + 460) = 67 kJ/mol, it is positive, therefore endothermic, this is TRUE

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