A chemical reaction releases 250 J of heat. If the reaction occurs at constant p
Practice Questions
Q1
A chemical reaction releases 250 J of heat. If the reaction occurs at constant pressure, what is the change in enthalpy?
-250 J
250 J
0 J
500 J
Questions & Step-by-Step Solutions
A chemical reaction releases 250 J of heat. If the reaction occurs at constant pressure, what is the change in enthalpy?
Step 1: Understand that 'ΔH' represents the change in enthalpy, which is a measure of heat content in a system.
Step 2: Recognize that when a chemical reaction occurs at constant pressure, the change in enthalpy (ΔH) is equal to the heat released or absorbed (q).
Step 3: Note that the problem states the reaction releases 250 J of heat. Since heat is released, it is considered negative in thermodynamics.
Step 4: Therefore, we write ΔH = q, which means ΔH = -250 J because the heat is released.
Enthalpy Change – The change in enthalpy (ΔH) at constant pressure is equal to the heat exchanged (q) during a reaction.
Sign Convention – Understanding the sign convention for heat: heat released is negative, while heat absorbed is positive.
