type the correct answer in the box. express the answer to two significant figures.\ngiven:\nn₂ + 3h₂ →…

type the correct answer in the box. express the answer to two significant figures.\ngiven:\nn₂ + 3h₂ → 2nh₃\n|bond|bond energy (kj/mol)|\n|----|----|\n|n≡n|942|\n|h - h|432|\n|n - h|386|\nuse the bond energies to calculate the change in enthalpy for the reaction.\nthe enthalpy change for the reaction is kilojoules.

type the correct answer in the box. express the answer to two significant figures.\ngiven:\nn₂ + 3h₂ → 2nh₃\n|bond|bond energy (kj/mol)|\n|----|----|\n|n≡n|942|\n|h - h|432|\n|n - h|386|\nuse the bond energies to calculate the change in enthalpy for the reaction.\nthe enthalpy change for the reaction is kilojoules.

Answer

Explanation:

Step1: Calculate energy to break bonds

For reactants, 1 mole of $N\equiv N$ and 3 moles of $H - H$ bonds are broken. Energy to break bonds = $942+3\times432$ $=942 + 1296$ $=2238$ kJ/mol

Step2: Calculate energy released when bonds are formed

For products, 2 moles of $NH_3$ are formed. Each $NH_3$ has 3 $N - H$ bonds, so total $N - H$ bonds formed is $2\times3 = 6$. Energy released when bonds are formed = $6\times386= 2316$ kJ/mol

Step3: Calculate enthalpy change

$\Delta H$ = Energy to break bonds - Energy released when bonds are formed $\Delta H=2238 - 2316=-78$ kJ/mol

Answer:

$-78$