According to table i, which equation represents a change resulting in the greatest quantity of energy released?
1. 2c(s) + 2h2(g) -> c2h4(g)
2. 2c(s)+3h2(g) -> c2h6(g)
3. n2(g) +3h2(g)-> 2nh3(g)
4. n2(g)+o2(g) -> 2no(g)

3. N2(g) +3H2(g)->2NH3(g)

Explanation:

Reactions can be broadly classified as endothermic and exothermic reactions. In the former, energy or heat is absorbed by the reactants and the enthalpy change of the reaction is positive. In the later, heat is released ans the enthalpy change of the reaction is negative.

For the given reactions, the enthalpy change or ΔH values are:

1. 2C(s) + 2H2(g) -> C2H4(g)        ΔH = +52.4 kJ

2. 2C(s)+3H2(g) -> C2H6(g)         ΔH = -84 kj

3. N2(g) +3H2(g)->2NH3(g)          ΔH = -91.8 kJ

4. N2(g)+O2(g) -> 2NO(g)            ΔH = +182.6 kJ

Reactions 1 and 4 are endothermic while reactions 2 and 3 are exothermic in which heat is released.

More negative the ΔH value, greater is the amount of heat released.

Thus, reaction 3, represents a change resulting in the greatest quantity of energy released

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.