Answer: C
Explanation:
In endothermic reactions, enthalpy is positive, and in exothermic reactions, enthalpy is negative, So, if enthalpy is positive, then it is an endothermic reaction, and hence is required for the reaction to occur.
The difference is due to the degree of dissociation of the substances. HCl dissociates completely into ions when added to water, while this is not the case for HC₂H₃O₂; therefore, HCl has a lower pH.
the first law says that the change in internal energy of a system is given by:
δ<span>E = δq + δw</span>
where δ<span>E is the i change in internal energy, </span>
<span>δq is the amount of thermal energy added to the system from the surroundings </span>
<span>δw is the l work done *on* the system *by* the surroundings. </span>
<span>For a system only undergoing expansion work,
δw = -p</span>δ<span>V, so: </span>
δE = δq - p δ<span>V </span>
when δV = 0, then δe=δq
