Why do reactions either give out or absorb heat?
3 marks · EasyThe reaction below takes place:
Answer the following questions:
State one bond broken during this reaction.
State one bond formed during this reaction.
Explain why energy is required for this reaction to occur.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) N–H bond
(b) N≡N or H–H bond
(c) Energy is needed to break bonds in ammonia molecules.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States an appropriate bond broken (N–H bond).
B2 (b) · 1 mark · States an appropriate bond formed (N≡N or H–H).
B3 (c) · 1 mark · Explains that energy is required to break bonds in the reactant (ammonia).
Worked solution
a) N–H bond in NH3. b) N≡N in N2 or H–H in H2. c) Because energy is needed to break the N–H bonds in ammonia.