Chemistry help. Moles, joules and all that. (1 Viewer)

[Memi]

Herro fellow BOS'ers~
I have a predicament on my hands! >_>
Okay, so I'm doing an assignment and we were asked to calculate the energy expenditure involved in the extraction of aluminium from its ore and I'm so confused D:

I've done some research and have figured out that there is approx. 350 gigajoules of energy per 1 tonne of aluminium.
I was told I would need to make it kj per mole, but why? O__o Is there a reason for it? And I'm confused as to how to do it T_T~

Help please? D: Thanks.

 

[slyhunter]

Hello fellow BOS'ers~
I have a predicament on my hands! >_>
Okay, so I'm doing an assignment and we were asked to calculate the energy expenditure involved in the extraction of aluminium from its ore and I'm so confused D:

I've done some research and have figured out that there is approx. 350 gigajoules of energy per 1 tonne of aluminium.
I was told I would need to make it kj per mole, but why? O__o Is there a reason for it? And I'm confused as to how to do it T_T~

Help please? D: Thanks.

Fixed.

 

[Memi]

Fixed.

Uh thanks?

 

[ohexploitable]

9.443 kJ mol^-1

 

[ohexploitable]

You need to make it kJ mol^-1 because it's the SI unit, it's just convention.

 

[Memi]

9.443 kJ mol^-1

Hm, how did you get that? >_> Sorry I'm really crap at the moles and all..

Wouldn't you first need to find the moles in 1 tonne Aluminium and then divide it by 350 giga joules? Or did I do it completely wrong?

 

[ohexploitable]

= 350 GJ / 1 t
= 350000 kJ / 1000000 g
= 0.35 kJ / 1 g

there are 26.98 g per mole of Al

.: 9.443 kJ / mol
.: 9.443 kJ mol^-1

 

[Memi]

= 350 GJ / 1 t
= 350000 kJ / 1000000 g
= 0.35 kJ / 1 g
.: 9.443 kJ / mol
.: 9.443 kJ mol^-1

Ah thanks a lot. Really appreciate it~ ^__^!

 

[kr73114]

is energy expenditure like energy considerations? i have a similar assignment except mine asks for energy considerations. what is that?