Respuesta :
Answer:
Q = 12.5 kJ
Explanation:
The expression to use to calculate Heat is:
Q = H° * n
Where:
Q: heat (J or kJ)
H°: enthalpy of reaction (kJ/mol)
n: moles
Now, as it was stated in the comments, the question is incomplete, and here is the missing part:
Given:
2A + B A2B (1)
H° = – 25.0 kJ/mol
2A2B 2AB + A2 (2)
H° = 35.0 kJ/mol
With these two reactions, we can calculate the heat.
Now, with the above two reactions, we need to get the general reaction (The one the question is giving), so, let's use (1) and (2) and do the sum of them:
2A + B -------> A2B H°1 = -25 kJ/mol
2A2B --------> 2AB + A2 H°2 = 35 kJ/mol
Now, we sum both equations, we can see that one A2B cancels out with one A2B from equation 2, so, the equation gives:
2A + B + 2A2B -------> 2AB + A2
And the enthalpy, it's just summed:
H°3 = -25 + 35 = 10 kJ/mol
Now with this value we can calculate heat:
Q = 10 * 2.5 = 25 kJ
However, in the reaction we have 2A, so it's not 1:1 mole ratio, but instead is 1:2, so this result we have to divide it between 2 so:
Q = 25 / 2 = 12.5 kJ
