Question

Which of these statements are true? Select all that apply.

Answer 1

In order to find the two statements, we must first define what the enthalpy of formation and the enthalpy of reaction mean.

Enthalpy of formation:
The change in enthalpy when one mole of substance is formed from its constituent elemetns at standard state.

Enthalpy of reaction:
The change in enthalpy when a reaction occurs and the reactants and products are in their standard states.

Now, we check the statements. The true ones are:

The Hrxn for C(s) + O₂(g) → CO₂(g) is the same as Hf for CO₂
This is true because the formation of carbon dioxide requires carbon and oxygen in their standard states.

The Hf for Br₂(l) is 0 kJ/mol by definition.
Because the bromine is present in its standard state, the enthalpy of formation is 0.

The Hrxn for the reaction 1.5H₂(g) + 0.5N₂(g) → NH₃(g) is the same as the Hf for NH₃(g)
The reactants and products are present in their standard state, and the reaction is the same as the one occurring during the formation of ammonia.

Answer 2

Answer:

1,3,6

Explanation: