For the following reactions, the δh° rxn is not equal to δh° f for the product except for

a. h2o (l) + 1/2 o2 (g) → h2o2(l)
b. n2 (g) + o2 (g) → 2no (g)
c. 2h2 (g) + o2 (g) → 2h2o (g)
d. 2h2 (g) + o2 (g) → 2h2o (l)
e. 2c(s, graphite) + 2h2(g) → c2h4 (g)

The correct option is: e. 2C(s, graphite) + 2H₂(g) → C₂H₄ (g)

Explanation:

The standard enthalpy of the reaction () is the change in enthalpy associated with a given chemical reaction. It can be calculated by the standard enthalpies of formation of the products and reactants.

The standard enthalpy of formation () of an elements that is present in its standard state is zero.

Therefore,

a. H₂O (l) + 1/2 O₂ (g) → H₂O₂(l)

Here, the

→

b. N₂ (g) + O₂ (g) → 2NO (g)

Here, the

→

c. 2H₂ (g) + O₂ (g) → 2H₂O (g)

Here, the

→

d. 2H₂ (g) + O₂ (g) → 2H₂O (l)

Here, the

→

e. 2C(s, graphite) + 2H₂(g) → C₂H₄ (g)

Here, the

→

2b2t

explanation:

2b2t

it is the most commonly accepted one