Higher chemitry

I've got a really hard question here, hope someone can help me here!

1. 2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(l) ∆H = -2600 kJ
The energy released when 0.5 mole of each gas is mixed and ignited is
A 260 kJ
B 520 kJ
C 650 kJ
D 1300 kJ

Reply 1

charco

Study Forum Helper

Original post by AimeeOceann

You understand that energy is an extensible property. In other words the amount is proportional to the number of moles reacting?

Reply 2

AimeeOceann

Yeah, is that like enthalpy of combustion?

Reply 3

charco

Study Forum Helper

Original post by AimeeOceann

Yeah, is that like enthalpy of combustion?

Yes. So your question requires that you identify the limiting reagent (Avogadro's law of reacting gases) and then apply the combustion enthalpy.

Reply 4

Davies Chemistry

Hi
That is quite tricky- it's all about identifyimg which reagent is in excess- the C2H2 in this case-there isn't enough oxygen to react with it all. See attachment for worked answer

Excess reagent.jpg122.6KB

Reply 5

charco

Study Forum Helper

Original post by Davies Chemistry

Hi
That is quite tricky- it's all about identifyimg which reagent is in excess- the C2H2 in this case-there isn't enough oxygen to react with it all. See attachment for worked answer

Please allow me to draw your attention to the study help guidelines:

"Do not post full solutions unless absolutely necessary. Instead, try to guide the person asking towards working out the answer themself."
https://www.thestudentroom.co.uk/wiki/Study_Help_Guidelines

Reply 6

AimeeOceann