Question

Instant help!
20cm3 of an unknown hydrocarbon needed 120cm3 of oxygen for complete combustion. 80cm3 of CO2 was produced. All volumes were measured at rtp. Find the formula of the hydrocarbon.

Answer 1

0.080L x 1mol /22.4L = 0.00357 moles of CO2

0.020L x 1mol /22.4L = 8.93 x 10^-4 mol hydrocarbon

0.120L x 1mol/22.4L = 0.005357 mol O2

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moles of CO2 = moles of C in the sample of hydrocarbon

(mol O2 x 2 ) - (mol CO2 x 2) = moles of H2O

mol of H2O x 2= moles of H in the sample

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moles of C in the sample of hydrocarbon / 8.93 x 10^-4 mol hydrocarbon= number of C per molecule

moles of H in the sample / 8.93 x 10^-4 mol hydrocarbon = number of H per molecule

Answer 2

I got C4H8

C4H8 + 6O2 -> 4 CO2 + 4H20

Answer 3

It's rtp not stp but I think I got it. Thank you.

Answer 4

https://en.wikipedia.org/wiki/C4H8

Answer 5

Wait...I don't get the second part.

Answer 6

what part?

Answer 7

Getting mol of H20

Answer 8

the moles of O2 you have to multiply by 2 to calculate the total number of oxygen atoms. The oxygen is going to form CO2 and H2O.
the CO2 has two atoms of oxygen by molecule and the water one

Answer 9

Are you using Avogadro's number in this???

Answer 10

no