LECTURE 1: HYDROCARBONS

Question 1

What type of bonds do alkanes have?

Answer 1

Single bonds

Question 2

What shape do four bonds around an alkane carbon have?

Answer 2

Tetrahedral

Question 3

What is the general formula for alkanes?

Answer 3

CnH2n+2

Question 4

What is the suffix for alkanes?

Answer 4

-ane

Question 5

What type of bonds do alkenes have?

Answer 5

double bonds

Question 6

What shape do the bonds around an alkene have?

Answer 6

trigonal planar

Question 7

What is the functional group of alkenes?

Answer 7

C=C functional group

Question 8

What is the general formula for alkenes?

Answer 8

CnH2n

Question 9

What is the suffix for alkenes?

Answer 9

-ene

Question 10

What type of bond do alkynes have?

Answer 10

triple bond

Question 11

What shape do the bonds around an alkyne have?

Answer 11

linear

Question 12

What functional group are alkynes?

Answer 12

C (triple bond) C functional group

Question 13

What is the general formula for alkynes?

Answer 13

CnH2n-2

Question 14

Suffix for alkynes?

Answer 14

-yne

Question 15

For carbons in a circle what comes before the suffix?

Answer 15

‘cyclo’

Question 16

Are alkanes polar or non-polar molecules?

Answer 16

non-polar

Question 17

What bonds do alkanes have?

Answer 17

weak dispersion forces

Question 18

BP/MP of alkanes?

Answer 18

low MP/BP to overcome weak dispersion forces

Question 19

Solubility of alkanes

Answer 19

insoluble in water since they are non-polar and cant form strong intermolecular forces with water (only weak dispersion forces)

Question 20

What is the density, conductivity and state of alkanes.

Answer 20

Density - low
Conductivity - poor
State - stable and unreactive

Question 21

Why does the BP/MP of alkanes increase as the carbon chain increases?

Answer 21

• larger molecules = more electrons, more instances of unequal electron sharing –> higher probability of temporary dipoles forming
  –> increases overall strength of the dispersion forces

Question 22

the four physical properties of alkenes and alkynes

Answer 22

1. Low MP/MP
2. Low density
3. Insoluble in water
4. Poor conductors in electricity

–> non-polar only have weak dispersion forces

Question 23

chemical properties of alkenes and alkynes

Answer 23

• unsaturated molecules therefore more reactive due to double and triple bonds between carbon

Question 24

What type of reactions can alkanes undergo?

Answer 24

• combustion (complete and incomplete)
• substitution

Question 25

Combustion reaction**

Answer 25

hydrocarbon + oxygen = carbon dioxide + water

Question 26

What is the condition of substitution reaction of alkanes?

Answer 26

- react SLOWLY with chlorine (Cl2) and bromine (Br2) - in the presence of UV light

Question 27

What type of reactions can alkenes undergo?

Answer 27

- combustion (complete and incomplete) - addition - hydrogenation - halogenation - hydrohalogenation - hydration - dehydration

Question 28

What happens in the addition reaction of an alkene?

Answer 28

The reaction double bond is broken to allow the carbons to bond with the compound.

Question 29

What happens in the hydrogenation of an alkene?

Answer 29

- It's the addition of hydrogen (H2) - In the presence of a Pt catalyst - The double bond is broke to allow more bonds with hydrogen

Question 30

What is hydrohalogenation?

Answer 30

The addition of a hydrogen halide such as HCl or HBr

Question 31

What are the conditions of hydration reaction of alkenes?

Answer 31

- in the presence of dilute H+ - there isnt a plus sign for anything - for the resultant molecule, the double bond is broken and there's an -OH group bonded to one of the carbons

Question 32

What are the conditions of dehydration reaction of alkenes?

Answer 32

- alkene + water --> (concentrated H2SO4 catalyst) the resultant molecule with have the water bonded to the opposite carbons. one side will have -OH and the other side will have a -H

Question 33

What reactions can alkynes undergo?

Answer 33

- combustion (complete and incomplete) - addition - hydrogenation - halogenation - hydrohalogenation - hydration

Question 34

The 3 conditions of hydrogenation of alkynes and explain what happens

Answer 34

- triple bond --> double bond --------> catalyst: H2/Pt - double bond --> single bond ---------> catalyst: H2/Pt Once the bonds are broken, allows hydrogens to be bonded - If you only want to go from triple to double bond, the catalyst is H2/ Lindlar's catayst

Question 35

The process of halogenation of alkynes

Answer 35

dont put a plus sign, just an arrow with Br2 on top and the double bond will e broken and two bromines will be bonded to the remaining double bonded carbons. do this process again to get down to single carbon bonds

Question 36

what is the condition for the hydrogen atom in the process of hydrohalogenation of an alkyne

Answer 36

the hydrogen from the the catalyst will bond to the carbon atom that has the closest hydrogen to it. "Hydrogen hangs with his homies"

Question 37

what are the catalysts for hydration of alkynes?

Answer 37

dilute HgSO4 and H2SO4 it should look like H2O, H2SO4/ HgSO4

Question 38

what is the product of hydration reaction of alkyne?

Answer 38

a carbonyl compound (C=O) --> meaning that the process immediately breaks 2 of the three bonds

Question 39

What is the process that oil refineries undertake to make higher demand oils

Answer 39

cracking

Question 40

List the disadvantages of using hydrocarbons in fuel?

Answer 40

- CO2 is produced from the complete combustion of hydrocarbons - contributes to the ENHANCED greenhouse effect - leads to rise in global temps - detrimental climate change - rising sea levels