Mole calculation question. (2 Viewers)

[turntaker]

I forgot how to do this, Help will be greatly appreciated.

At Orica's Botany Bay ethylene production plant, each 1000 t of ethane produces about 780 t of ethylene.

a) Using the mole concept and molecular masses calculate the amount of hydrogen you would expect produced with each 780 t of ethylene.

b)Most reactions involving carbon compounds do not give all of the desired products. As well as ethylene and hydrogen what mass of other substances would you expect produced from each 1000 t of ethane?

 

[Rajiv321]

I don't know if this is right but this is what i did:
a)
ethylene - C2H4
MM = 28
Amount of C = 24
Amount of H = 4
therefore (780 * 4)/28 = 111.4t
but C2H6 -> C2H4 + H2 (I think)
therefore (1000-780)+111.4 = 331.4t

 

[happypeople]

Hey!

I got the following answer:



I'm not sure if the image is clear enough, but the answer I obtained was 167 tonnes of total hydrogen produced with each 780 tonnes of ethylene (includes hydrogen gas and the hydrogen that makes up ethylene) (to 3 sig figs, the lowest amount of sig figs in the given question).

IMPORTANT NOTE: to calculate moles, the units of the "mass" is in GRAMS (not tonnes or kg etc)
1000 tonnes = 1000 000 000 grams = 1000x10^6 grams
780 tonnes = 780 000 000 grams = 780x10^6 grams

Therefore the moles of ethane should actually be 33.2579..x10^6
And the moles of ethylene should actually be 27.8055...x10^6
(Moles of ethane is still bigger than moles of ethylene)

However, if you use those ^ numbers in the subsequent calculations, the total amount of hydrogen becomes 167277912.4 grams = 167.27... tonnes. So my final answer has not changed since I used the same units (tonnes) in my calculations of the moles of ethane and ethylene, and my calculations of the amount of hydrogen produced (as seen in the photo attached).

In school however, you must show the conversion of tonnes into grams in your answer, and then work out the moles.

Hope this helps! Good luck with your studies!