Question

With the equation C3H8+5O2=3CO2 + 4H2O, what volume of carbon dioxide would result from burning 500. g of C3H8?

Answer 1

here is how i would do this;

* convert the mass of c3h8 into the number of c3h8 in moles (divide the mass by the molecular weight)
* the equation has already been balanced, and it says that 3 mol of co2 forms from 1 mol of c3h8. so this tells us that the number of co2 formed will be three times the number of c3h8 burned.
* so we have the number co2 produced. the volume depends on not just the number but the pressure and temperature. for example: at 1 atm of pressure, 1 mol of gas particles has a volume of about 24 L at 300K, but the volume is 240L at 3000K.

so we seem to be stuck. my guess: either there is info missing, or we are supposed to assume values for the pressure and temp.

in either case, we would use the ideal gas law to find the volume from the number of co2.

Answer 2

then, what would the answer be?

Answer 3

well, the code of conduct http://openstudy.com/code-of-conduct says we are supposed to help by guiding, not by giving quick answers.

how may i help you in this sense?

Answer 4

I think I have it set up right: 500.(1 mol/ 44.1 g)(3 mol CO2/1 mol C3H8)

Answer 5

that looks right to me, that's the number of co2 created.

Answer 6

normally, i would use the ideal gas law to find the volume from the number of gas particles, but we know neither pressure nor the temperature. does this question come from a book?

Answer 7

No, the teacher wrote the question.

Answer 8

this is gas stoichiometry.

Answer 9

grams to liters

Answer 10

okay. this is burning (or combustion), so the co2 that comes out will be a gas not a liquid or solid.

because, it's a gas, the co2 density depends on the pressure and the temperature. has your teacher covered the ideal gas law?

Answer 11

yes

Answer 12

my guess: the teacher forgot, or we are supposed to assume values for P and T. let's pretend to the latter.

Answer 13

in an experiment, we could capture this gas in a beaker and adjust the volume so that the pressure is the same as the atmosphere (approx. 1 atm). let's assume the room temperature is 25 deg Cel or approx. 298 K.

do you know how we would apply the ideal gas law to find the volume in this scenario?

Answer 14

PV=nRT

Answer 15

This problem is more of a stoichiometry problem. not really an ideal gas problem.

Answer 16

you are right--if we just want the number of molecules.

once the question asks for the volume of a gas, it becomes an ideal gas problem.

so the unknown is V, and P = 1 atm, T = 298 K, and R is the gas constant.

Answer 17

so, im just confused on how this would be set up.

Answer 18

so we want V, and

V = n * R * T / P

i would plug in:
R = 0.0821 L atm mol^-1 K^-1
n = number of co2 in moles
T = 298 Kelvin
P = 1 atm

the answer comes out to be about 830 Liters. it's huge--that's because the amount of gas is huge--(500 g / 44 g per mol) x 3 is about 30 mol.

Answer 19

i am going to take my leave at this point. other people might be able to help you more, but i really think your teacher left out the information (by accident).