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AS-Level Chemistry question

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???
Reply 1
Avatar for RoseVet
RoseVet
15
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.
Reply 2
Avatar for j_kingzz
j_kingzz
OP
11
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
Reply 3
Avatar for RoseVet
RoseVet
15
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?
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
Reply 5
Avatar for j_kingzz
j_kingzz
OP
11
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 😓
Reply 6
Avatar for j_kingzz
j_kingzz
OP
11
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
Reply 7
Avatar for RoseVet
RoseVet
15
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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