SC22 & SC23 & SC24 - Hydrocarbons / Alcohols and Carboxylic Acids / Polymers Flashcards Preview

Edexcel GCSE Chemistry COPY > SC22 & SC23 & SC24 - Hydrocarbons / Alcohols and Carboxylic Acids / Polymers > Flashcards

Flashcards in SC22 & SC23 & SC24 - Hydrocarbons / Alcohols and Carboxylic Acids / Polymers Deck (78)
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1

SC22a - What is a hydrocarbon?

A molecular compound containing only hydrogen and carbon atoms

2

SC22a - What is the functional group of an alkane?

Trick question. They have no functional group

3

SC22a - What is the general formula of an alkane?

CnH2n+2

4

SC22a - What are the first four prefixes for all the homologus serieses?

  1. Meth- (Don't do drugs)
  2. Eth-
  3. Prop-
  4. But-

5

SC22a - According to the IUPAC, how are hydrocarbons (and many other molecule types) named?

  • Prefix showing its number (e.g. Meth- is 1)
  • Suffix showing its homologous series (e.g -ane is alkane)

6

SC22a - Why is an alkane saturated?

It only contains single bonds between carbon bonds meaning it can't open out and bond to more atoms

7

SC22a - What are the displayed and molecular formulae of the first four alkanes?

8

SC22a - What is a functional group?

The part of a molecule that identifieis it with its specific functional group and is responsible for its chemical properties

(e.g all carboxylic acids have COOH )

9

SC22a - What is the functional group of an alkene?

All alkenes contain one double covalent bond between two carbon atoms

10

SC22a - What is the general formula of an alkene?

CnH2n

11

SC22a - Why is there no 'methene' ?

A meth- alkene would have 1 carbon atom but to be an alkene, it would need a double bond between carbons, which can't happen, unless there are 2+ carbon atoms

12

SC22a - Why is an alkene unsaturated?

It contains a double covalent bond between two carbon atoms, meaning that the bond can be opened out and another atom can bond to it.

13

SC22a - What are the molecular and displayed formula of the first 3 alkenes (remember there isn't a 'methene')

14

SC22a - What is an isomer?

The same molecule with their functional group placed in different places.

e.g. below is but-1-ene (as the group is in it's first possible position) and but-2-ene (with the group in the second position)

15

SC22a - Why are there no isomers of ethene and propene?

  • Ethene only has 2 carbon atoms and so the double bond can only be in one place
  • Propene has 3 carbon atoms and so the double bonds can be in 2 places however, positioning them in these two places would make reflections of the same molecule

16

SC22b - How do alkanes and alkenes react in combustion?

  • When heated up sufficiently, hydrocarbons will oxidise, and combust, reacting with the oxygen in the air and releasing energy
  • When sufficient oxygen is present, all the hydrocarbon will oxidise (complete combustion)
    • Hydrocarbon + Oxygen → Carbon dioxide + water
  • When there is a lack of oxygen, not all of the hydrocarbon will oxidise (incomplete combustion) Carbon monoxide and/or carbon aswell, instead of just carbon dioxide

17

SC22b - How can you tell if a chemical is an alkene or an alkane?

  • When placed in and mixed with bromine water, an alkane won't react and no change will be observed
  • However, the double bond in an alkene, will open out and react with the bromine water taking it out of the water and it goes from orange-brown to colourless

18

SC22b - What colour is bromine water?

Orange-brown

19

SC22b - What is an addition reaction

When more than one reactant reacts to form a larger product and no other products

20

SC22b - What is the word equation for the addition reaction between ethene and bromine water?

Ethene + Bromine water → 1,2 dibromoethane

(Don't know if this is required knowledge)

21

SC23a - What are the uses of ethanol?

  • Alcoholic beverages
  • Fuel for vehicles
  • Material in raw industry

22

SC23a - What is ethanol made from?

  • Sugars. These are small soluble substances that belong to a group called carbohydrates
  • Seeds contain a carb called starch (a long polymer).
  • Germinating seeds allows enzymes to break down the starch into sugars
  • Fermentation uses enzymes in yeast to turn the sugars into ethanol

23

SC23a - What plants are used to make different alcoholic beverages?

  • Beer - Barley seeds
  • Wine - Grapes
  • Whisky - Barley seeds
  • Vodka - Wheat seeds

24

SC23a - Describe the fermentation process of ethanol

  • Glucose → Ethanol + Carbon dioxide
  • Yeast containing enzymes that will turn the glucose solution into ethanol
  • Heat source keeps the solution at the optimum temperature of around 25 C
  • Air lock lets out carbon dioxide, but doesn't let any oxygen in, allowing anaerobic respiration to occur

25

SC23a - What is the problem with the fermentation process and how is this overcome?

Only alcohol of 15% concentration can be produced (or else the yeast enzymes will be killed). So, fractional distillation is used to obtain high concentrations of alcohol.

Ethanol's b.p. of 78 C is less than water and so it evapourates first and condenses into a distillate of high conc. ethanol

26

SC23b - What is an organic compound?

A compound with a central framework of carbon atoms but with hydrogen and other atoms attached

27

SC23b - What is the functional group of the alcohols homologous series?

-OH atoms on the end of the compound

28

SC23b - What is the general formula of alcohols?

CnH2n+1

29

SC22a - What are the first four alkanes?

  • Methane
  • Ethane
  • Propane
  • Butane
  • -ane is prefix

30

SC22a - What are the first three alkenes?

  • Ethene
  • Propene
  • Butene
  • -ene is prefix