Question
Which of the following is a statement of Hess's law? If a reaction is carried out in a series of steps, the Delta H for the reaction will equal to of the enthalpy changes for the individual steps. The Delta H for a process in the forward direction is equal to magnitude and opposite in sign to the Delta H for the process in the reverse direction. The Delta H of the reaction depends on the physical states of the reactants and products. If a reaction is carried out in a series of steps, the Delta H for the reaction will equal the product of the enthalpy changes for the individual steps. The Delta H for a process in the forward direction is equal to the Delta H for the process in the reverse direction. In the reaction below, Delta H_f degree is zero for Ni (s) + 2CO (g) + 2PF_3(g) rightarrow Ni (CO)_2 (PF_3))2 (1) Ni (CO)_2 (PF_3)_2 (1) CO(g) Ni(s) PF_3(g) both CO (g) and PF_3(g)
Explanation / Answer
17. Hess's law is
" If a reaction is carried out in a series of steps, the enthalphy change for the reaction will equal the sum of the enthapy changes for the individual steps"
So option A is correct.
18. Standard enthapy of formation of any solid in standard state is zero. So Ni(s) is having zero value of standard heat of formation.
So option "C" is correct.