bond energy calculations

Question 1

N2+3H2 bonds must be broken in the haber process. what type of reaction is this

Answer 1

endothermic as energy is being taken in

Question 2

in 2NH3 new bonds are made. what type of reaction is this

Answer 2

exothermic as energy is released

Question 3

calculate deltaH in the haber process (N2+3H2-->2NH3)
-Bond values are as follows:
N=N 945
H-H 436
N-H 391

Answer 3

• N=N+3(H-H)–>2x3(N-H)
• 945+3(436)=2253
• 2x3(391)=2346
• Bonds broken (endo)=2253 (left hand side)
• Bonds made (exo)= 2346 (right hand side)
• overall more energy is released when the bonds are made in ammonia than the energy needed to break the bonds in nitrogen and hydrogen (93kj/mol)

Question 4

what is the haber process

Answer 4

nitrogen+hydrogen–>Ammonia

N2+3H2–>2NH3