question help (1 Viewer)

[rubyp]

The question is: using the figure of 1372 kJ.mol^-1 for the molar heat of combustion of ethanol, calculate the heat produced from the combustion of 2 moles of this alcohol.

I'm just a little unsure of the steps I have to take

 

[KingOfActing]

1372 kJ of heat is produced for every mole that undergoes combustion, therefore 2*1372 = 2744 kJ of heat is produced for 2 moles.

 

[Shoesta]

Ruby as if you wouldn't get this... You would if you were good at Chemistry.

 

[rubyp]

thank you! I thought it was a trick question

 

[rubyp]

Shoey... who's coming first??

 

[Shoesta]

Shoey... who's coming first??

Shoesta to you

 

[Shoesta]

1372 kJ of heat is produced for every mole that undergoes combustion, therefore 2*1372 = 2744 kJ of heat is produced for 2 moles.

How many moles of ethanol will need to be burnt to produce 4459kJ of heat?

 

[ml125]

How many moles of ethanol will need to be burnt to produce 4459kJ of heat?

4459(kJ)/1372(kJ/mol) = 3.25 moles

 

[Shoesta]

4459(kJ)/1372(kJ/mol) = 3.25 moles

Okay, 1 more...

How do you do the calculations for the molar heat of combustion for propanol 1 and heptanol 1??

Thanks heaps!!!!!

 

[ml125]

Okay, 1 more...

How do you do the calculations for the molar heat of combustion for propanol 1 and heptanol 1??

Thanks heaps!!!!!

It's basically the same as molar heat of combustion for ethanol

1. Find the heat of reaction (ΔH = mcΔT)
2. Divide by mass of alkanol used (to get ΔH/g)
3. Multiply (2) by molar mass of alkanol (to get ΔH/mol)