# PV=nRT question aqa

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Thread starter 2 years ago
#1
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?
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2 years ago
#2
Are you sure the water is gaseous?
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Thread starter 2 years ago
#3
(Original post by jason0597)
Are you sure the water is gaseous?
The question says ''assume the water is gaseous''
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2 years ago
#4
(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.
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Thread starter 2 years ago
#5
(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
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Thread starter 2 years ago
#6
(Original post by BabaTheBast*rd)
"It burns... forming three gases" Yes ******
Leave him, alone man
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2 years ago
#7
Hes a tryhard 12 year old trying to answer an A level question...
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Thread starter 2 years ago
#8
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'
Last edited by deathnote123; 2 years ago
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2 years ago
#9
(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
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Thread starter 2 years ago
#10
(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)''
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2 years ago
#11
(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
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Thread starter 2 years ago
#12
(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
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2 years ago
#13
(Original post by BabaTheBast*rd)
Yes ******
(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.
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Thread starter 2 years ago
#14
(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 ****** at all!
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2 years ago
#15
(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 ******ed

i think all 3?
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2 years ago
#16
(Original post by BabaTheBast*rd)
then we have 3 possibilities
1 - u dont do chemistry
2 - u bad at chemistry
3 - u are ******ed

i think all 3?
OK, well, if you think shouting insults has any meaning then go ahead and do whatever you like.
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2 years ago
#17
(Original post by jason0597)
OK, well, if you think shouting insults has any meaning then go ahead and do whatever you like.
I just hate all humen because all so bad.
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2 years ago
#18
(Original post by BabaTheBast*rd)
I just hate all humen because all so bad.
So you were trolling all this time?
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Thread starter 2 years ago
#19
(Original post by BabaTheBast*rd)
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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