Recognize different formats of expressing heat of reaction

The heat of reaction (∆H) represents the amount of heat energy gained or lost during a chemical reaction. It can be expressed in different formats depending on the specific information provided. Let's analyze each option and identify the equivalent equations for the given reaction:

a) N2(g) + 2O2(g) → 2NO2(g) ΔH = +68 kJ: This equation is an equivalent representation of the given reaction. It explicitly states that the heat of reaction (∆H) is +68 kJ, indicating that the reaction releases 68 kJ of heat energy.

c) 1⁄2N2(g) + O2(g) → NO2(g) ΔH = + 34 kJ: This equation is also an equivalent representation of the given reaction. It differs from the original equation by using the stoichiometric coefficients to balance the reaction. It shows that the heat of reaction (∆H) is +34 kJ, indicating the release of 34 kJ of heat energy.

d) N2(g) + 2O2(g) → 2NO2(g) ΔH = +68 kJ/mol N2: This equation is another valid representation of the given reaction. It includes the molar quantity of nitrogen gas (N2) and specifies the heat of reaction (∆H) per mole of nitrogen gas. It indicates that for each mole of N2, the heat of reaction is +68 kJ.

f) N2(g) + 2O2(g) → 2NO2(g) ΔH = +34 kJ/mol NO2: This equation is also an equivalent representation of the given reaction. It includes the molar quantity of nitrogen dioxide (NO2) and specifies the heat of reaction (∆H) per mole of nitrogen dioxide. It indicates that for each mole of NO2, the heat of reaction is +34 kJ.

The remaining options (b) and (e) are not equivalent to the given reaction: b) N2(g) + 2O2(g) → 2NO2(g) ΔH = -68 kJ: This equation incorrectly states that the heat of reaction (∆H) is -68 kJ, suggesting that the reaction absorbs 68 kJ of heat energy. This contradicts the given information of the reaction releasing heat energy.

e) 1⁄2N2(g) + O2(g) → NO2(g) ΔH = −34 kJ: This equation incorrectly states that the heat of reaction (∆H) is -34 kJ, indicating that the reaction absorbs 34 kJ of heat energy. Again, this contradicts the given information of the reaction releasing heat energy.

In summary, the equivalent equations to the given reaction N2(g) + 2O2(g) + 68 kJ → 2NO2(g) are options a), c), d), and f). These equations accurately represent the given reaction and provide information about the heat of reaction (∆H) in various formats, including the heat change per mole of N2 or NO2.