Unsaturated Hydrocarbons

Question 1

What are unsaturated hydrocarbons

Answer 1

alkenes and alkynes
They do not contain the max num of hydrogens

Question 2

Which is more reactive alkenes/alkynes or alkanes

Answer 2

aklenes alkynes

Question 3

What is the gen formula for alkenes

Answer 3

Cn H2n

Question 4

What is the gen formula for alkanes

Answer 4

CnH2n+2

Question 5

What is the gen formula for akynes

Answer 5

CnH2n-2

Question 6

Rule for nomanclature with dbl or trpl bond

Answer 6

make sure the multiple bond has the lowests number possible

Question 7

What do you do with the name if there is more than one multi bond

Answer 7

2 double bonds = alkadiene
3 double bonds = alkatriene
Same rules for alkynes

put an a after the prefix
Hexa-2,4-diene

Question 8

How do you name cycloalkenes

Answer 8

make sure the multi bond is in between carbon 1 and 2
if there is no branch you do not need to say where the multi is

Question 9

what is the smallest possible cycloalkyne

Answer 9

Cyclooctyne but it is still very reactive

Question 10

Chem prop of alkenes

Answer 10

similar to alkanes
First 3 alkenes (ethene, propene and butene) are gases at room temp
Boiling point is slightly lower than alkanes
change in pos of dbl bond affects melting point
multi bond can be broken and another element or group can be attached
more reactive than alkanes
combustable
highly flammable

Question 11

Chem prop of alkynes

Answer 11

insoluble in water
first 3 are gases at standard temp
has higher boiling point than alkanes
The linear structure of alkynes and the nature of triple bond makes them more attracted to each other.
multi bond can be broken and another element or group can be attached
more reactive than alkanes
combustable
highly flammable

Question 12

What is an isomer

Answer 12

has the same chem formula but different shape

Question 13

Constitutional/Structural isomers

Answer 13

Constitutional/Structural isomers : different connectivity
when the atoms are joined up in a different order

Question 14

stereoisomers

Answer 14

Stereoisomers : same connectivity; different arrangement of atoms in space
happens when you have a multi bond, the formula is the same but multi bond cannot flip one of its branches like a single bond can. ( cis and trans)

Question 15

How to name geometric isomers (stereoisomers)

Answer 15

if the branches are on opposite sides of the dbl bond then its trans
if the branches are on the same side of the dbl bond then is cis
cis and trans are prefix
the branches can be carbons, (cis-But-2-ene/trans-But-2-ene)
trans-1,2-dichloroethene
cis -1,2 - dichloroethene