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Chem C4-C6 > C6.2- Organic chemistry (homologous series) > Flashcards

C6.2- Organic chemistry (homologous series) Flashcards

c6.2.1 - c6.2.4 (alkanes, alkenes, alcohol, carboxylic acids)

1
Q

define an alkane

A

a compound which contains only hydrogen and carbon atoms (bonded together by single covalent bonds)

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2
Q

acronym to remember first 5 members of alkane/alkene/alcohol/carboxylic acid series

A 
M y
E lephant
P umps 
B alloons
P ainlessly 
Monkeys Eat Peanut Butter
Meth- 
eth- 
prop-
but-
pent-
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3
Q

what is the molecular formula for an alkane?

A

C H

n 2n+2

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4
Q

draw out the displayed formula for propane

A 
H H H
     |   |   |
H-C-C-C-H
     |   |   | 
    H H H
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5
Q

why are alkanes described as saturated hydrocarbons

A
  • they are joined by single covalent bonds

- and each carbon atom is bonded to 4 other atoms

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6
Q

write out the word equation for complete combustion of alkanes

A

alkane + oxygen -> water + carbon dioxidef

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7
Q

how do alkanes combust in a poor supply in oxygen? (write out the word equation)

A

alkane + oxygen -> carbon monoxide + carbon + water

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8
Q

define an alkene

A

an unsaturated hydrocarbon made of ONLY hydrogen and carbon atoms, which contain one double carbon carbon covalent bond

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9
Q

what is the molecular formula for alkenes?

A

C H

n 2n

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10
Q

draw out the displayed formula for butene

A 
H H H H  
     |   |   |   |
H-C-C=C-C-H
     |           |
    H         H

C4H8

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11
Q

what is different about the first 4 alkene molecules compared to alkanes?

A
  • there is no methane
  • as 2 carbon atoms must be present for a double carbon molecule to be formed
  • to produce an alkane
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12
Q

how do alkenes react with plentiful oxygen?

A

alkene + oxygen -> carbon dioxide + water

SAME AS ALKANE

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13
Q

how do alkenes combust with a limited supply of oxygen?

A

alkene + oxygen -> carbon monoxide + carbon + water

SAME AS ALKANE

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14
Q

define a functional group

A

atom, or group of atoms, or type of bond in a molecule that is responsible for the characteristic reactions of the substance

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15
Q

what allows alkenes to undergo a wider range of reactions?

A

a double carbon bond functional group

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16
Q

what are addition reactions, and give two examples of them

A
  • when an atom/group of atoms combine with a molecule to form a larger molecule (with NO OTHER PRODUCT)
  • reaction with alkenes + bromine water
  • reaction with alkenes + hydrogen
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17
Q

what can the addition reaction between bromine water and alkenes be used to detect?

A
  • test for unsaturation (ie. whether hydrocarbon is an alkene or not)
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18
Q

describe how the addition reaction with bromine-water works (not in terms of bonds)

A
  • bromine turns colourless with alkenes
  • stays orange-brown with alkanes
  • bromine reacts with alkenes, no reaction with alkanes
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19
Q

describe what happens when hydrogen reacts with an alkene, and what the name for that type of reaction is

A
  • called an addition reaction

- an alkane is formed

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20
Q

write down the word equation for an addition reaction with hydrogen and alkene

A

alkene + hydrogen -> alkane

21
Q

how do you identify if something is an alcohol (suffix)

A

ends with ‘ol’

ie. butanol

22
Q

what is the functional groups of alcohols?

- and what is it called

A

‘OH’

- called the ‘hydroxyl’ group

23
Q

what is the molecular formula for alcohols?

A

C H OH

n 2n + 1

24
Q

draw out ethanol

and state one thing that is special about how it is drawn out

A

C H OH
2 5

     H    H 
      |      |
H--C----C---O----H
      |      |
     H    H
  • the OH are separate at the side
25
Q

write out the word equation for the complete combustion of an alcohol

A

alcohol + oxygen -> water vapour + carbon dioxide

26
Q

write out the word equation for the incomplete combustion of an alcohol

A

alcohol -> water vapour + carbon monoxide + carbon (ie. soot)

27
Q

how do you identify if something is part of the carboxylic acid homologous series? - name

A

ends in ‘anoic’ acid

28
Q

what is the functional group of a carboxylic acid?

- and whats special about tit

A

-COOH

C=O double bond at the top

29
Q

what is the molecular formula for carboxylic acids?

A

C H COOH

n 2n + 1

30
Q

why can carboxylic acids take part in different reactions to alkenes and alkanes?

A

as they have a COOH functional group

31
Q

draw out the structural formula for methanoic acid

A

HCOOH
…….O
…….||
H - C - O - H

  • remember it only has 1 carbon atom, and all carboxylic acids must have a -COOH functional group (so Cn = C0)
32
Q

draw out ethanoic acid

A 
.......H....O
........|.....||
H - C - C - O - H
........|
.......H

CH COOH
3

33
Q

draw out butanoic acid

A 
H  H   H     O
       |    |     |      ||
H - C - C - C - C - O - H
       |     |     |
      H    H   H

C H COOH
3 7

34
Q

name the first 4 carboxylic acids

A

methanoic acid, ethanoic acid, propanoic acid, butanoic acid

35
Q

how are carboxylic acids made?

A

when alcohols are oxidised using potassium manganate (VII)

36
Q

describe an experiment to produce ethanoic acid from ethanol

A

1) acidify potassium manganate VII with dilute sulfuric acid
2) and add acidified potassium manganate VII oxidising agent to the ethanol and warm it in a water bath

3) colour changes from purple to very pale pink - therefore an acidified solution is made
(Colour change occurs as manganate(VII) ions are purple in solution, and are reduces to very pale pink manganese(II) ions when acidified potassium manganate(VII) oxidises ethanol to ethanoic acid)

37
Q

safety when making a carboxylic acid from an alcohol?

A
  • wear eye protection
  • stir reaction carefully (can be violent)
  • potassium manganate can stain clothing + hands
38
Q

what can a carboxylic acid also be described as?

A

a weak acid (therefore reacts with metals, bases in the same way)

39
Q

what do salts produced with a carboxylic acid have the ending of?

ie. ethanoic acid + sodium carbonate
(write out all products of the reaction)

A

‘oate’

makes:
sodium ethanoate + water + carbon dioxide

40
Q

How to form a carboxylic acid

A

Oxidise an alcohol

- oxidising agent - sodium dichromate or potassium manganate

41
Q

Colour change of sodium dichromate

A

Bright orange - dark green

42
Q

Colour change of potassium Manganate

A

Purple - colourless

43
Q

Complete combustion of ethane symbol equation (incl state symbols)

A

ethane + oxygen → carbon dioxide + water

C2H6(g) + 3½O2(g) → 2CO2(g) + 3H2O(l)

44
Q

Complete combustion of ethene symbol equation

A

ethene + oxygen → carbon dioxide + water

C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(l)

45
Q

Complete combustion of ethanol symbol equation

A

Ethanol + oxygen -> carbon dioxide + water

C2H5OH + 3O2 -> 2CO2 + 3H2O

46
Q

Ethanoic acid + sodium carbonate symbol equation

State symbols

A

Ethanoic acid + sodium carbonate -> sodium ethanoate + water + carbon dioxide

2CH3COOH(aq) + Na2CO3(aq) -> 2CH3COONa(aq) + H2O(l) + CO2(g)

47
Q

Tell about the reaction between alkenes and bromine

A

(Alkenes react with bromine in addition reactions to form colourless dibromo compounds)

48
Q

Ethene + bromine

Word equation + symbol equation + displayed

A

Ethene + bromine —> dibromoethane

C2H4 + Br2 —> C2H4Br2

….H..H
…..|….|…
H-C=C-H

+
Br-Br

—->
….H..H
…..|….|…
H-C-C-H
….|…..|
….Br..Br
49
Q

Functional group of alkenes?

What its allows?

A

Carbon-carbon double bond, C=C

It lets alkenes undergo addition reactions

Chem C4-C6 (19 decks)

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