Can someone help me with this Chemistry Question Please?? THanks!?

Question

The reusable booster rockets of the space shuttle use a mixture of aluminium and ammonium perchlorate as fuel. An equation for the reaction is:

3Al (s) + 3NH4ClO4 (s) --> Al2O3 (s) + 3NO (g) + 6H2O (g) + 2677 kJ

Calculate how much heat is released when the following quantities of aluminium are consumed according to the above equation:

(a) 1 mol
(b) 1 kg

Please help me work out this question because I don't know how to do them...THANKS! :)

Answer 1

the amount of heat released by the reaction is related to the amount of stuff present. think fire. When you have a fire in your fireplace, it gives off heat, some amount. But if you made the fire 10 times bigger, you would get 10 times more heat.

So - right now, the amount of heat released, 2677 kJ is related to 3 moles of Al

So set up a conversion - start with what you want to convert, we want to covert 1 mol Al

1mol Al x (2677 kJ/3 moles Al) = 892.3 kJ of heat released

or you could say -892.3 kJ (negative means heat released.

We do the SAME thing with the kg, working through a slightly longer conversion - start again with what we want to convert - the 1 kg

1 kg Al x (1000 grams/ 1kg) x (1 molAl/26.98 grams Al) =

37.06 moles of Al

now convert that using the kJ heat/3 mol Al in our balanced reaction

37.06 moles Al x (2677 kJ/3 mole Al) = 33,073.8 kj released

3.307 x 10^4 kJ heat released or -3.307 x 10^4 kJ

Answer 2

The convention is to express the heat released on the basis of 1 mole of product (Al2O3). Thus, if one mole of Al is used, only 1/3 mole of Al2O3 is produced, and the heat released is 1/3 that cited.

In a like manner, you can do the same for 1 kg of Aluminum, find the number of moles, compute the number of molesof Al2O3 formed, and multiply that number by the 2677 kJ.

Answer 3

when 1mol is used then 2677/3 kj of heat is released. when 1 kg is used then 1000/(mol wt of AL) is no of moles hence energy is (2677 * (no of moles))/3