Q3. This question is about the reaction given below.
CO(g) + H2O(g) + CO.(g) +H,(9)
Enthalpy data for the reacting species are given in the table below.
Substance
CO(g)
H. O(g)
CO. CO)
H (9)
ΔΗ.
/ kJ mol-
-110
-242
-394
0
The standard enthalpy change for this reaction of carbon monoxide and steam is
А
+42 kJ mol-
B
-42 kJ mol
С
+262 kJ mol
D
-262 kJ mol
(Total 1 mark)

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.