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PV=nRT question aqa

So, I tried this question out to find the total volume of gases in a reaction. The question is:
''Nitromethane, CH3NO2, is used as an ‘energy rich’ fuel for motor-racing. It burns in oxygen forming three gases.
2CH3NO2(l) + 1½O2(g) 2CO2(g) + 3H2O(g) + N2(g)
(i) A 1.00 mol sample of nitromethane was burned in oxygen forming the products shown in the equation above. Calculate the total volume of gases produced at 298 K and 100 kPa (assume that the water is gaseous)''

In the mark scheme, it says for the total moles of gas produced equals 3, shouldn't it be 6 as 2CO2 (g) + 3H20 (g) + 1N2 (g) gives 6 Moles of gas?
Are you sure the water is gaseous?
Original post by jason0597
Are you sure the water is gaseous?


The question says ''assume the water is gaseous''
Original post by deathnote123
So, I tried this question out to find the total volume of gases in a reaction. The question is:
''Nitromethane, CH3NO2, is used as an ‘energy rich’ fuel for motor-racing. It burns in oxygen forming three gases.
2CH3NO2(l) + 1½O2(g) 2CO2(g) + 3H2O(g) + N2(g)
(i) A 1.00 mol sample of nitromethane was burned in oxygen forming the products shown in the equation above. Calculate the total volume of gases produced at 298 K and 100 kPa (assume that the water is gaseous)''

In the mark scheme, it says for the total moles of gas produced equals 3, shouldn't it be 6 as 2CO2 (g) + 3H20 (g) + 1N2 (g) gives 6 Moles of gas?

Its 1 mol of 2CH3NO2. So 1 mol of co2, 1.5 mol of h20, 0.5 mol of n2. This adds up 1+1.5+0.5=3mol.
Original post by BabaTheBast*rd
Its 1 mol of 2CH3NO2. So 1 mol of co2, 1.5 mol of h20, 0.5 mol of n2. This adds up 1+1.5+0.5=3mol.


Oh yes, makes sense now... didn't think that mattered
Original post by BabaTheBast*rd
"It burns... forming three gases" Yes retard

Leave him, alone man :frown:
Hes a tryhard 12 year old trying to answer an A level question...
The next part says
''This combustion reaction is very exothermic and reaches a temperature of 1000 K. Determine the total volume of gases when the temperature is raised to 1000 K at a constant pressure. (If you have been unable to determine a volume in your answer to part (a)(i), you may assume it to be 8.61 × 10–4 m3 but this is not the correct answer).''

I did 0.0743 x 8.31 x 1000/298 but in mark scheme, they don't multiply by the 8.31. Is there a reason?
'edit: I divided by 298K by accident not 100,000Pa'
(edited 5 years ago)
Original post by deathnote123
The next part says
''This combustion reaction is very exothermic and reaches a temperature of 1000 K. Determine the total volume of gases when the temperature is raised to 1000 K at a constant pressure. (If you have been unable to determine a volume in your answer to part (a)(i), you may assume it to be 8.61 × 10–4 m3 but this is not the correct answer).''

I did 0.0743 x 8.31 x 1000/298 but in mark scheme, they don't multiply by the 8.31. Is there a reason?

The markscheme might have the answer for usong 8.61 instead of the actual answer.

V=(nRT)/P
Original post by BabaTheBast*rd
The markscheme might have the answer for usong 8.61 instead of the actual answer.

V=(nRT)/P


This is the mark scheme...

''(a) (i) Moles of gas produced = 3 (1)
PV = nRT (1)
V = nRT/P = 3 × 8.31 × 298/100000 (1) = 7.43 × 10–2 m3 (1)
(ii) 7.43 × 10–2 × 1000/298 = 0.249 m3 (1)''
Original post by deathnote123
This is the mark scheme...

''(a) (i) Moles of gas produced = 3 (1)
PV = nRT (1)
V = nRT/P = 3 × 8.31 × 298/100000 (1) = 7.43 × 10–2 m3 (1)
(ii) 7.43 × 10–2 × 1000/298 = 0.249 m3 (1)''

Yes. V=nRT/P
n=3, R=8.314, T=1000, P=100000
Original post by BabaTheBast*rd
Yes. V=nRT/P
n=3, R=8.314, T=1000, P=100000


Yeah thanks, I don't know why I divided by 298K... I'm struggling to concentrate cause I'm sick, along with a confusing mark scheme lol
Original post by BabaTheBast*rd
Yes retard

Original post by BabaTheBast*rd
Hes a tryhard 12 year old trying to answer an A level question...

Actually I'm a Y13 student. And there's no need to be so rude.
Original post by jason0597
Actually I'm a Y13 student. And there's no need to be so rude.


Ignore it, I don't think you're a retard at all! :smile:
Original post by jason0597
Actually I'm a Y13 student. And there's no need to be so rude.

then we have 3 possibilities
1 - u dont do chemistry
2 - u bad at chemistry
3 - u are retarded

i think all 3?
Original post by BabaTheBast*rd
then we have 3 possibilities
1 - u dont do chemistry
2 - u bad at chemistry
3 - u are retarded

i think all 3?

OK, well, if you think shouting insults has any meaning then go ahead and do whatever you like.
Original post by jason0597
OK, well, if you think shouting insults has any meaning then go ahead and do whatever you like.

:frown: I just hate all humen because all so bad.
Original post by BabaTheBast*rd
:frown: I just hate all humen because all so bad.

So you were trolling all this time?
Original post by BabaTheBast*rd
:frown: I just hate all humen because all so bad.


Hope you get the help you need... I know exactly how it feels trust me but rubbing your insecurities on others makes it worse. Watch some netflix, youtube, TV to cool down and watch some self-motivating, self-esteem boosters (that's what I do), all the best you can speak to me!!

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