Type the correct answer in the box. express the answer to two significant figures.
given:
n2 + 3h2 → 2nh3
bond bond energy (kj/mol)
n≡n 942
h–h 432
n–h 386
use the bond energies to calculate the change in enthalpy for the reaction.
the enthalpy change for the reaction is
kilojoules.

-78

Explanation: I got this correct on Edmentum.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2