important : selective school half yearly question (1 Viewer)

[clicker]

the compound cumene contains only carbon and hydrogen.
combustion of 71.5 g of cumene produces 235.6 g of CO2 and 64.3g of H2O.
what is its molecular formula?

 

[clicker]

thats not the right answer
i suggest since it is an alkene the ratio of C to H is CnH2n

 

[funking_you]

• This is systematically known as isopropyl benzene, its extended molecular formula is C₆H₅CH(CH₃)₂, or simply C₉H₁₂.

• So the combustion reaction would be
  C₉H₁₂(g) + 12O₂(g) --> 9CO₂(g) + 6H₂O(g)

• That 'general formula' for alkenes, is really only vaid for linear hydrocarbons with one double bond in them.

• To illustrate this point, draw 1,2-propene (which is a a linear chain of 3 carbon atoms, with 2 double bonds present.

You will not be test or expected to know such compounds as 'cumene', i think you teacher is just trying to be funny



George