Consider the following thermochemical equation: N 2 ( g ) + 2O 2 ( g ) 2NO 2 ( g
ID: 904980 • Letter: C
Question
Consider the following thermochemical equation:
N2(g) + 2O2(g) 2NO2(g); H° = 66.2 kJ
From this equation, we may conclude that 66.2 kJ is the quantity of heat that is
lost to the surroundings when 1 mol of O2 is consumed at constant pressure.
lost to the surroundings when 1 mol of NO2 is formed at constant pressure.
gained from the surroundings when 2 mol of NO2 is formed at constant pressure.
gained from the surroundings when 1 mol of NO2 is formed at constant pressure.
lost from the surroundings when 2 mol of NO2 is formed at constant pressure.
A.lost to the surroundings when 1 mol of O2 is consumed at constant pressure.
B.lost to the surroundings when 1 mol of NO2 is formed at constant pressure.
C.gained from the surroundings when 2 mol of NO2 is formed at constant pressure.
D.gained from the surroundings when 1 mol of NO2 is formed at constant pressure.
E.lost from the surroundings when 2 mol of NO2 is formed at constant pressure.
Explanation / Answer
H° = 66.2 kJ is the heat of reaction under standard conditions. Positive value of H° indicates that products have greater enthalpy than reactants or reaction is endothermic i.e. heat is gained from surroundings. Since, H° = 66.2 kJ is for the reaction, hence, it indicates heat gained from the surroundings when 2 moles of NO2 is formed at constant pressure.
Therefore, correct answer is option C: gained from the surroundings when 2 mol of NO2 is formed at constant pressure.