Why is standard enthalpy change 0 at 298 and 1 atm pressure?.?

Anonymous

Why not? They had to pick some point to declare it zero. The enthalphy value by itself is meaningless other than how it with another value gives you a change in enthalphy. You'd get the same answers if they defined standard enthalphy as 100 at 298 and 1 atm or any other T and P.