Consider the Following Changes at Constant Temperature and Pressure

question 60

Multiple Choice

Consider the following changes at constant temperature and pressure:
H₂O(s) → H₂O(l) ; ΔH₁
H₂O(l) → H₂O(g) ; ΔH₂
H₂O(g) → H₂O(s) ; ΔH₃
Using Hess's law,the sum ΔH₁ + ΔH₂ + ΔH₃ is

• A)equal to zero.
• B)sometimes greater than zero and sometimes less than zero.
• C)less than zero.
• D)cannot be determined without numerical values for ΔH.
• E)greater than zero.