# AS-Level Chemistry question

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#1
What is the total number of moles of gases produced when 10cm^3 of nitroglycerine explode? (The density of nitroglycerine is 1.59gcm^-3)The answers: 0.508 mol but I don't know how to get there???
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1 month ago
#2
Does it give you the molecular formula? Because you can use density= mass / volume to work out the mass, and then if you have the formula you can calculate Mr and use n= m/mr.
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#3
(Original post by RoseVet)
Does it give you the molecular formula? Because you can use density= mass / volume to work out the mass, and then if you have the formula you can calculate Mr and use n= m/mr.
C3H5N3O9 so Mr is 227.11 but ive tried that method and i get 0.07001
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1 month ago
#4
(Original post by j_kingzz)
C3H5N3O9 so Mr is 227.11 but ive tried that method and i get 0.07001
Did you convert the mass into kg? Even then that wouldn’t get the right answer though would it? Do you get no other information?
1
1 month ago
#5
you have 15.9g of nitroglycerine
15.9/227.1 = 0.07 mol

When nitrous compounds EXPLODES what are the products? Nitrogen gas, CO2, H2O!
C3H5N3O9

But the bad part of this question is to assume each molecule decomposes cleanly into 3CO2+2H2O+N2+HNO . So 7 part gas per part nitroglycerin. Times 0.07 by 7 you get 0.49 which is close enough
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#6
(Original post by RoseVet)
Did you convert the mass into kg? Even then that wouldn’t get the right answer though would it? Do you get no other information?
Nope 😓
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#7
(Original post by AndyChow)
you have 15.9g of nitroglycerine
15.9/227.1 = 0.07 mol

When nitrous compounds EXPLODES what are the products? Nitrogen gas, CO2, H2O!
C3H5N3O9

But the bad part of this question is to assume each molecule decomposes cleanly into 3CO2+2H2O+N2+HNO . So 7 part gas per part nitroglycerin. Times 0.07 by 7 you get 0.49 which is close enough
hold on yh we did sorry i get it now so basically because the balanced equation is C3H5N3O4 --> 3CO2 + 2.5H2O + 1.5N2 +0.25O2 you have 7.25 part gas per part nitoglyceride and you multiply that to the 0.07001 to get 0.508
1
1 month ago
#8
(Original post by j_kingzz)
hold on yh we did sorry i get it now so basically because the balanced equation is C3H5N3O4 --> 3CO2 + 2.5H2O + 1.5N2 +0.25O2 you have 7.25 part gas per part nitoglyceride and you multiply that to the 0.07001 to get 0.508
Yay, well done!
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