Chemistry Brainscape Organic

Question 1

What is the functional group of an alkene?

Answer 1

C=C

Question 2

What is the functional group of an alcohol?

Answer 2

O-H

Question 3

What is the functional group of an alkane?

Answer 3

C-H

Question 4

What is the functional group of an aldehyde?

Answer 4

O=C-H

Question 5

What is the functional group of a carboxylic acid?

Answer 5

O=C-OH

Question 6

What is the functional group of an ester?

Answer 6

O=C-O

Question 7

What is the functional group of a halogenoalkane?

Answer 7

X-C-H

Question 8

What is the functional group of a ketone?

Answer 8

C=O

Question 9

What is the functional group of a nitrile?

Answer 9

carbon triple bonded to nitrogen

Question 10

What is the functional group of an amine?

Answer 10

H-N-H

Question 11

Is an alkene saturated or unsaturated?

Answer 11

unsaturated

Question 12

What is the double bond consisted of?

Answer 12

A sigma and a pi bond

Question 13

What is a sigma bond?

Answer 13

A single covalent bond formed by the overlap of S-S, S-P, or P-P orbitals. This forms a region of electron density concentrated between two nuclei.

Question 14

What is a pi bond?

Answer 14

A double covalent bond formed by the sideways overlap between two p orbitals. This forms two regions of electron density above and below the plane of a molecule.

Question 15

Why is there restriction around the double bond?

Answer 15

The regions of high electron density both between, above and below the molecules prevents rotation.

Question 16

Why does E/Z isomerism (stereoisomerism) arise?

Answer 16

Due to the restriction of rotation around the double bond, and the presence of different groups attached to the carbons at the end of the bond.

Question 17

How does increasing the number of carbon atoms in an alkene affect its properties?

Answer 17

The more carbon atoms, the more intermolecular forces there are, increasing the overall strength of bonding (cumulative significance). This increases the melting and boiling points.

Question 18

Are alkenes soluble in water?

Answer 18

No, only in organic solvents

Question 19

Why are alkenes insoluble in water?

Answer 19

They are not polar, so are unable to form hydrogen bonds with water

Question 20

Why are alkenes non-polar?

Answer 20

The C-C and C-H bonds have a very small electronegativity difference, therefore they are not polar bonds.

Question 21

What does solubility mean?

Answer 21

The energy taken to break bonds in both molecules has to be equal to the energy taken to form new bonds between them

Question 22

Why are non-polar compounds insoluble in water?

Answer 22

The only forces in non-polar compounds are London forces while in water there are hydrogen bonds. The energy taken to break and form London forces is far less than the energy taken to break and form hydrogen bonds.

Question 23

What are the differences in combustion of alkenes and alkanes?

Answer 23

Alkenes burn with a smokier/sootier flame, due to the higher carbon percentage

Question 24

Describe the reaction of addition to hydrogen to alkenes

Answer 24

The alkene’s double bond is removed, producing the respective alkane

Question 25

What are the conditions and reagents for addition of hydrogen to alkenes?

Answer 25

either 1) room temperature with a platinum/palladium catalyst or 2) 150C with a nickel catalyst

Question 26

Why is a solid metal catalyst used for catalytic hydrogenation?

Answer 26

better because the catalyst is easier to extract and has no changes to it, also better for adsorption

Question 27

What is the addition reaction of hydrogen to alkenes also known as?

Answer 27

Catalytic hydrogenation

Question 28

Describe the reaction of addition to halogens to alkenes

Answer 28

The double bond is removed, and the two halogen atoms added to the chain, producing a dihalogenoalkane (e.g. dichloroalkane)

Question 29

What is the mechanism for addition of halogens to alkenes?

Answer 29

Electrophilic addition

Question 30

What is produced when adding steam to alkenes?

Answer 30

An alcohol

Question 31

What is the condition for addition of steam to alkenes?

Answer 31

Acid catalyst (provides adsorption)

Question 32

What is the mechanism for addition of hydrogen halides to alkenes?

Answer 32

Electrophilic addition

Question 33

What are the tests between saturated and unsaturated hydrocarbons?

Answer 33

Bromine water - turns colourless from brown-yellow Potassium manganate (VII) turns from purple to colourless

Question 34

Describe the process of fractional distillation

Answer 34

1) mixture is heated then passed into the fractioning column 2) the separation of fractions depends on their boiling point 3) substances with low boiling points will evaporate to gases and pass out of the top 4) substances with high boiling points either condense at the middle or stay at the bottom as solids

Question 35

What is the trend up the fractioning column?

Answer 35

higher flammability, lower boiling point, lower viscosity

Question 36

How are fuels obtained from crude oil?

Answer 36

fractional distillation -\> cracking -\> reforming

Question 37

What is fractional distillation?

Answer 37

separates similar size hydrocarbons from the mixture of hydrocarbons because they are used as fuels

Question 38

What is cracking?

Answer 38

the conversion of large hydrocarbons into smaller ones by breakage of C-C bonds

Question 39

What is reforming?

Answer 39

the conversion of straight chain alkanes into branched/cyclic alkanes and aromatic hydrocarbons

Question 40

Why is reforming used?

Answer 40

the new products burn more cleanly and efficiently due to their higher octane number making them more stable

Question 41

Why are alkanes good fuels?

Answer 41

they burn readily in the presence of oxygen, and the combustion is highly exothermic

Question 42

Describe the reaction behind bromine water turning colourless in the presence of an alkene

Answer 42

When bromine water is shaken with ethene (example), electrophilic addition occurs. Because there are both water molecules and bromine ions present, they can both act as electrophiles.

Question 43

What are the two products of the electrophilic addition of bromine water and ethene?

Answer 43

1,2- dibromoethane (halogenoalkane) and 2-bromoethanol (alcohol). More 2-bromoethanol is produced more because there are more water molecules.

Question 44

Why are halogenoalkanes polar?

Answer 44

There is a significant electronegativity between Carbon and its Halogen atom, therefore producing a permanent dipole.

Question 45

Compare the boiling points of halogenoalkanes and their parent alkanes and explain the trend.

Answer 45

Halogenoalkanes have higher boiling points. This is because alkanes have only London forces present, whereas H-Alkanes have permanent dipole-dipole forces (stronger).

Question 46

Can halogenoalkanes mix with water?

Answer 46

No, because the dipole-dipole forces are much weaker than hydrogen bonds (solubility rule)

Question 47

What is the solubility rule?

Answer 47

In order for two substances to fully dissolve, the energy taken to break the bonds in both substances must be equal to the energy released in making the bonds between them. This is why water does not mix with alkanes/halogenoalkanes. Hydrogen bonds require a lot more energy to break and make than London forces.

Question 48

Describe the process needed for alkene -\> halogenoalkane

Answer 48

* addition of a hydrogen halide * room temperature

Question 49

Describe the process needed for alkane -\> halogenoalkane.

Answer 49

* heating or UV light * chlorine or bromine * leading to free radical substitution

Question 50

Describe the process needed for alcohol -\> halogenoalkane.

Answer 50

* addition of phosphorus or hydrogen halides

Question 51

Draw the mechanism for the free radical substitution of alkanes and halogens.

Answer 51

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