4.1 Basic concepts & Hydrocarbons

Question 1

What’s a Homologous series?

Answer 1

substances in a series with the same functional group and successive members differ only by a CH2

Question 2

What’s an Aliphatic hydrocarbon?

Answer 2

when carbons joined in either straight or branched chains

Question 3

What’s an Alicyclic hydrocarbon?

Answer 3

when carbons joined in ring structure

Question 4

What’s an Aromatic hydrocarbon?

Answer 4

when carbons joined with at least 1 benzene ring in the structure

Question 5

What’s the difference between a saturated and unsaturated hydrocarbon?

Answer 5

Saturated= only single bonds
Unsaturated= contains at least 1 double bond

Question 6

What’s a functional group?

Answer 6

group of atoms responsible for a characteristic reaction of a compound

Question 7

What’s a General formula?

Answer 7

simplest algebraic formula for a homologous series

e.g Cn H2n+2

Question 8

What’s a Displayed formula?

Answer 8

shows positions of atoms and every bond

Question 9

What’s a Structural formula?

Answer 9

minimum ordered arrangement of atoms

e.g. CH3CH2CH3

Question 10

What’s a Molecular formula?

Answer 10

shows number and type of atoms

e.g C6H12O6

Question 11

What’s an Empirical formula?

Answer 11

show the smallest whole number ratio of atoms of the elements in a compound

Question 12

What’s a skeletal formula?

Answer 12

simplified formula that uses line and doesn’t show hydrogen’s in alkyl chain

Question 13

What’s a Structural isomer?

Answer 13

molecules with same molecular formula but different structural formulas

Question 14

What’s a Stereoisomer?

Answer 14

molecules with same molecular & structural formula but different arrangements of atoms in space?

Question 15

What e/z isomerism?

Answer 15

type of stereoisomer where different groups arranged around a c double bond

Question 16

What Cis-Trans isomerism?

Answer 16

type of E/Z isomerism but the 2 substituents on each carbons the same

Question 17

What would an ‘e’ isomer look like?

Answer 17

e for enemies

highest priority substituents on opposite ends(diagonal)

Question 18

What would a ‘Z’ isomer look like?

Answer 18

highest priority substituents on the same side of the double bond(straight line)

Question 19

What would a Cis-isomer look like?

Answer 19

same group same side (straight line)

basically z

Question 20

What would a Trans-isomer look like?

Answer 20

same groups on opposite sides

basically e

Question 21

What’s Homolytic fission, what’s the product?

Answer 21

two covalent bonds break and electrons split equally to creates radicals

Question 22

What’s Heterolytic fission, what’s the product?

Answer 22

two covalent bonds break and electrons split unequally

• creates Ions (positive and negative)

Question 23

Summarise Free Radical substitution to form a Haloalkane

Answer 23

1. Initiation- generate radicals with UV light
2. Propagation- 2 steps
   • radical + alkane→ alkyl radical + acid
   • alkyl radical + halogen → new radical + haloalkane
3. termination- reactions to remove all remaining radicals

Question 24

What’s an Alkane?

Answer 24

Saturated hydrocarbon homologous series

Question 25

What's are some features of Alkanes?

Answer 25

* longer chains = increasing boiling point * only weak London(dispersion) forces * non polar * only σ bonds

Question 26

What happens in Complete combustion?

Answer 26

enough oxygen for substance to burn with clean blue flame and produces max thermal energy + co2 + water

Question 27

What happens in Incomplete combustion?

Answer 27

not enough oxygen for substance to burn. makes orange flame and produces less energy CO2 + water + CO

Question 28

What's an Alkene?

Answer 28

Unsaturated hydrocarbon homologous series

Question 29

What's are some features of Alkanes?

Answer 29

* longer chains = increasing boiling point * can undergo addition reactions * more reactive * contain both π and σ bonds * double bonds so can show sterioisomersm

Question 30

What's a Nucleophile?

Answer 30

electron pair donors | atoms with lone pair electrons & negative ions

Question 31

What's an Electrophile?

Answer 31

electron pair acceptors | positve ions & partial positives

Question 32

How do you go from Alkane to Alkene?

Answer 32

cracking | • High temperatures

Question 33

How do you go from Alkene to Alkane?

Answer 33

Hydrogenation (H2) of Alkenes | • High temperature and nickel catalyst

Question 34

What the difference between halogenation of Alkanes and Alkenes?

Answer 34

``` Alkanes = free radical substitution reaction (needs UV ) alkenes = simple addition reaction ```

Question 35

In Alkene addition mechanisms how do the arrows move

Answer 35

from double bond to electrophile | then nucleophile to carbocation

Question 36

How do you go from an Alkene to an Alcohol?

Answer 36

Hydration with steam(H2O) • High temperature and pressure • Phosphoric acid catalyst

Question 37

How does the type of carbocation affect its stability?

Answer 37

the less hydrogens around the carbocation the more stable | ∴ tertiary carbocation most stable & primary least stable

Question 38

What happens when many Alkenes join together?

Answer 38

forms a polymer

Question 39

What is a Repeating unit?

Answer 39

The structure that repeat over and over again | closed of in brackets with n on outside

Question 40

Why are Polymers useful?

Answer 40

versatile with many uses, are also saturated compounds so they're vey stable

Question 41

Why are landfills a bad way to dispose Polymer waste?

Answer 41

when we bury the rubbish, conditions become anaerobic which reduces the decomposition rate of biodegrable materials

Question 42

Why is combustion a bad way to dispose Polymer waste?(2)

Answer 42

• Polymers release green house gases when burnt(CO2) - Greenhouse gases contribute too climate change • Other plastics may release other toxic gases

Question 43

What are some ways we can combat Polymer waste?

Answer 43

* reduce unnecessary usage * reusing plastics * recycling * using biodegradable polymers * using photodegradable polymers

Question 44

What are Bio & Photo degradable polymer?

Answer 44

* Bio= broken down by microorganisms & the environment | * Photo= breakdown using energy wavelengths similar to light

Question 45

What's a bioplastic?

Answer 45

Material made from renewable source that biodegradable

Question 46

Why is the difference between branched and unbranched hydrocarbons

Answer 46

• Unbranched isomers tend to be longer, ∴ Higher Bp & Mp • Unbranched has more points of contact • Unbranched has stronger/more induced dipole dipole forces

Question 47

uncertainty Eq?

Answer 47

(absolute uncertainty *2)/ value measured