# chemistry

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#1
8) A 27.0 g sample of an unknown hydrocarbon, CxHy, was burned completely in excess
oxygen to form 88.0 g of carbon dioxide and 27.0 g of water.
[Molar masses / g mol–1: CO2= 44; H2O = 18]
Which of the following is a possible formula of the unknown hydrocarbon?
A CH4
B C2H6
C C4H6
D C6H6

the answer is C but can someone explain with steps how to find it out?
0
2 years ago
#2
(Original post by enigmatic17)
8) A 27.0 g sample of an unknown hydrocarbon, CxHy, was burned completely in excess
oxygen to form 88.0 g of carbon dioxide and 27.0 g of water.
[Molar masses / g mol–1: CO2= 44; H2O = 18]
Which of the following is a possible formula of the unknown hydrocarbon?
A CH4
B C2H6
C C4H6
D C6H6
Write the equation and balance it. Then use mass=molar mass x no. of moles (rearranged) to find the moles of co2 and h2o. Then by the initial balanced ratio, scale the moles to find the moles of the hydrocarbon - then reuse the above mass equation to find the molar mass of the hydrocarbon. You should then find it matched one of the options. Hope this helps If not, feel free to ask more
0
#3
(Original post by Ljg2015)
Write the equation and balance it. Then use mass=molar mass x no. of moles (rearranged) to find the moles of co2 and h2o. Then by the initial balanced ratio, scale the moles to find the moles of the hydrocarbon - then reuse the above mass equation to find the molar mass of the hydrocarbon. You should then find it matched one of the options. Hope this helps If not, feel free to ask more
I got it, thanks a lot
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