Homologous series of the alkanes and alkenes

In organic chemistry there are 2 types of hydrocarbons. One of them is sturated hydrocarbon, which is (for example) alkane and the other one is unsatured hydrocarbon, which is (for example) alkene. Please carefully watch the video to complete easy task on next page.. 

 

 

  1. which one (alkane or alkene) is unsaturated hydrocarbon?
  2. which natural gas is often used as a fuel in homes for heating/cooking?
  3. In which homologous series belongs ethane?
  4. How many carbon and hydrogen atoms are in propane?
  5. Write alkenes general formula
  6. Write alkanes general formula
  7. which one (alkane or alkene) has a double bond?
  8. How many carbon and hydrogen atoms are in propene?

Alkanes:

  • formula - CnH2n+2
  1. for example: if you have 4 carbon atoms(C), then hydrogen atoms(H) will be - 2x4+2=8+2=10 (formula - C4H10 and name for that will be butane). on first and last carbon atom will be 3 hydrogen atoms, but on each second and third carbon atom will be 2 hydrogen atoms.

Alkenes:

  • formula - CnH2n
  1. for example: if you have 3 carbon atoms(C), then hydrogen atoms(H) will be - 2x3=6, and if double bond is between first and second carbon atom, then formula will be - C3H6 and name for that will be propene. So if there is double bond between first and second carbon atom, then on first carbon atom will be 2 hydrogen atoms, but on secons carbon atom will be only one hydrogen atom, because there are already double bond on one side and on other side one single bond.

 

 

answers to the task

  1. alkene
  2. methane
  3. alkane
  4. 3 carbon atoms and 8 hydrogen atoms (C3H8)
  5. C(n)H(2n)
  6. C(n)H(2n+2)
  7. alkene
  8. 3 carbon atoms and 6 hydrogen atoms (C3H6)

if you had 6 and more answers right - well done! If not, then you should pratice more and pay more attention to the video. 

After all you can see that:

Alkanes:

  • saturated hydrocarbon
  • formula - CnH2n+2
  • sinble bonds

Alkenes:

  • unsaturated hydrocarbon
  • formula - CnH2n
  • 1 double bond

But there are also:

  • unstaurated hydrocarbons -  alkynes, alkadienes
  • saturated hydroarbon - cycloalkane
  • aromatic hydrocarbon - benzene ring

all information from:

https://www.youtube.com/watch?v=Sfm3eHe57PU

and from school textbook for class 11