Determine the heat given off to the surroundings when 9.873 g of aluminum reacts according to the equation 2Al + Fe2O3 → Al2O3 + 2Fe, ΔH°rxn= -849.1 kJ/mol.

Question

asked Oct 20, 2019 205k views

1 Answer

Erik Fischer · Answer 1 · 2019-10-25T11:38:09+0000

Answer : The heat given off to the surroundings will be, -155.38 KJ

Solution : Given,

$\Delta H^o_(rxn)=-849.1KJ/mole$

Mass of aluminium = 9.873 g

Molar mass of aluminium = 27 g/mole

First we have to calculate the moles of aluminium.

$\text{ Moles of Al}=\frac{\text{ Mass of Al}}{\text{ Molar mass of Al}}=(9.873g)/(27g/mole)=0.366moles$

The given balanced reaction is,

$2Al+Fe_2O_3\rightarrow Al_2O_3+2Fe$

From the reaction, we conclude that

2 moles of aluminum releases heat energy = -849.1 KJ

0.366 moles of aluminium releases heat energy =
(-849.1KJ)/(2moles)* 0.366moles=-155.38KJ

Therefore, the heat given off to the surroundings will be, -155.38 KJ