Properties of Alkanes

C-C

S... hydrocarbons

Least r...

Part of same ... series (same f... ... - each successive member differs by ...)

saturated, reactive, homologous, functional groups, CH2

Bonding: alkanes

T...

Bond angle:

4 ... bonds - can r...

sp³ orbitals form σ bonds.

tetrahedral, 109.5, sigma, rotate

S-orbital shape:

P-orbital shape:

sphere, dumbbell

Orbital overlaps:

s-orbital + s-orbital =

s-orbital + p-orbital =

p-orbital + p-orbital = ALL EQUAL ? BOND

sigma

Are alkanes polar or non polar?

Why? (C=2.5, H=2.1) - C + H have similar ....

non polar, electronegativities

Non-polar -> ... in water -> h....

London forces between alkane molecules = ... than H-bonds in water (polar) -> cannot form ... bonds with water

insoluble, hydrophobic, weaker, hydrogen

Alkanes are insoluble in ... but soluble in ... ... s...

water, non polar solvents

Longer chain = more l... ... -> ... boiling point/mp - more s... c... = more ... required to break forces

london forces, higher, surface contact, energy

Shorter chain: less ... ... between molecules -> ... boiling point/mp - less s... ... + less ... required

london forces, lower, surface contact, energy

Unbranched = higher s... c... - more ... required to break forces -> ... boiling point/mp

surface contact, energy, higher

Branched = lower s... ... - less ... required to break forces -> ... bp/mp

(as molecules can't p... closely)

surface contact, energy, lower, pack

Chemical properties:

Test: B... ...

Alkane: stays ...

Alkene: turns ...

-> shows alkanes = u... as

C-C + C-H bonds = s... + have high b... e...

bromine water, orange, colourless, unreactive, strong, bond enthalpy

C-C + C-H bonds = strong, but can be broken via:

1. C...

2. React w h...

combustion, halogens

Complete combustion: ... supply of oxygen

Products when alkane + O2:

excess, CO2 + H2O

Most of time, all products = ?

gaseous

Complete combustion of methane:

CH4 + 2O2 -> ? + ?

CO2 + 2H2O

Complete combustion of ethane:

2C2H6 + 7O2 -> ? + ?

4CO2 + 6H2O

Complete combustion of propane:

C3H8 + 5O2 -> ? + ?

3CO2 + 4H2O

Incomplete combustion: ... supply of oxygen

Products:

limited, CO + C

CO = ?

C = ?

carbon monoxide, soot

Incomplete combustion of methane:

CH4 + O2 -> ? + ? + ?

CO + C + H2O

Incomplete combustion of ethane:

C2H6 + 2O2 -> ? + ? + ?

CO + C + 3H2O

Incomplete combustion of propane:

C3H8 + 3O2 -> ? + ? + ?

2CO + C + 4H2O

Other possible products:

NOₓ (n... o...) <-formed from .. + .. in air reacting

High .... + p... in engines

nitrogen oxides, N2 + O2, temperatures, pressure

N₂ + O₂ -> ?

Reacts w water + more O2: 4NO + 2H2O + 3O2 -> 4HNO3 (a... r...)

2NO, acid rain

SO₂ (s... d...)

Formed from s... i... in fuel

sulfur dioxide, sulfur impurities

S + O2 -> ?

S + 1/2O2 -> ?

Reacts w water + more O2: SO3 + H2O -> H2SO4 (s... a...)

SO2, SO3, sulfuric acid

Pollutants:

CO2 - greenhouse gas - absorbs .. -> global warming

H2O - greenhouse gas

Particulates -> b... difficulties

NO2 + SO2 - a... r...

CO - t... gas

Unburnt hydrocarbons -> s... - (g... d...)

IR, breathing, acid rain, toxic, smog, global dimming