Question

question 3 (1 point)
what is the standard enthalpy of formation for n2 and h2 in the following equation 2 nh3(g) → n2(g) + 3 h2(g)
the standard enthalpy of formation of nh3 is -45.9 kj/mol
it cant be predicted
zero
+45.9 kj/mol
-45.9 kj/mol

Explanation:

Step1: Recall definition of standard - enthalpy of formation

The standard enthalpy of formation ($\Delta H_f^{\circ}$) of an element in its standard state is zero.

Step2: Identify standard states of N2 and H2

Nitrogen ($N_2$) and hydrogen ($H_2$) are elements. At standard conditions, $N_2$ and $H_2$ are in their standard states (gaseous state for both). So, $\Delta H_f^{\circ}(N_2,g)=0$ and $\Delta H_f^{\circ}(H_2,g)=0$.

Answer:

Zero