N А
E
H
B
7 주
F
с
J
D
t
G
с
|
B
Н
A
S
Source: Examiners sketch
1.1.1
Identify pressure belts A, B, C, D.
(4 X 1) (4)
А
B.​

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen