The phrase “the heat absorbed or released by a system undergoing a physical or chemical change at constant pressure” is

a. the change in enthalpy of the system.
b. the change in internal energy of the system.
c. the definition of a state function.
d. the temperature change of the system.
e. a statement of Hess’s law.

i want the answer dumb butt not a source

Can you explain why?

To determine the correct answer, let's break down the question and the options provided:

The phrase "the heat absorbed or released by a system undergoing a physical or chemical change at constant pressure" refers to a specific concept in thermodynamics.

a. The change in enthalpy of the system is related to heat transfer at constant pressure, so this option could be a possibility.

b. The change in internal energy of the system is a different concept, not directly related to heat transfer at constant pressure, so this option is less likely to be the correct answer.

c. The definition of a state function describes a property that depends only on the current state of a system and not on the path taken to reach that state. While heat transfer at constant pressure is related to a state function, it is not a definition of it, so this option is also less likely.

d. The temperature change of the system is not directly stated in the original phrase, so this option is less likely to be the correct answer.

e. Hess's law refers to the principle that the enthalpy change for a process is the same regardless of the number of steps it takes to go from the initial to final state. While heat transfer is involved in Hess’s law, it is not a direct statement of the law itself, so this option is less likely.

Based on this analysis, the most likely answer is a. the change in enthalpy of the system. To get to this answer, you need to understand the concept of enthalpy, which is a measure of the heat energy absorbed or released by a system at constant pressure. Therefore, the correct answer is a. the change in enthalpy of the system.

Here is some reading for you. Pay particular attention to paragraphs 4 and 5.

http://en.wikipedia.org/wiki/Enthalpy