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GCSE Chemistry > C10 - Organic Reactions > Flashcards

C10 - Organic Reactions Flashcards

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1
Q

What do organic compounds form the basis of?

A

All living things

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2
Q

What atoms do all organic molecules contain?

A

Carbon atoms.

Carbon atoms form the backbone of all organic molecules.

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3
Q

What is a ‘functional group’?

A

The area of a molecule that is reactive and gives a ‘family’ of organic molecules its distinctive reaction characteristics.

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4
Q

What is the functional group in alkenes?

A

The ‘C==C’ double carbon bond.

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5
Q

What do chemists call a ‘family’ of organic compounds with the same functional group?

A

A homologous series.

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6
Q

What are some examples of homologous series?

A

Alkanes - Methane, Ethane, Propane, Butane, Pentane

Alkenes - Ethene, Propene, Butene, Pentene

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7
Q

Why are Alkenes very reactive?

A

Because of the ‘C==C’ double carbon bond.

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8
Q

Why are Alkenes rarely burned?

A

Alkenes release far less energy than alkanes.

Alkenes tend to undergo incomplete combustion - so they burn with a smoky flame.

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9
Q

What are alkenes useful for making/producing?

A

Alkenes are so valuable in making polymers and plastics.

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10
Q

What type of reaction do alkenes undergo?

A

Addition Reactions

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11
Q

What happens in an addition reaction of an alkene?

A

The C==C double carbon bond undergoes the addition.

The C=C double carbon bond becomes a single C–C bond, and other atoms join onto the 2 carbon atoms.

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12
Q

What is the general formula/template for an addition reaction?

A

General Formula:
X Y
| | | |
C==C + X—Y —> —C—C—
| | | |

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13
Q

How do alkenes react with the halogens? (C2, Br2, I2) Give an example:

A
  • The C==C double bond becomes a single bond.
  • The number of hydrogen atoms stays the same.
  • The 2 halogen atoms are added on to the displayed formula.

Example:

Ethene + Bromine —> *Dibromoethane

C2H4 + Br2 —> C2H4Br2

*Dibromoethane is colourless because of the presence of bromine (think about alkene test in orange coloured bromine water).

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14
Q

How do alkenes react with hydrogen, (H2)? What conditions must the reaction be under? Give an example:

A

-Alkenes react with hydrogen (H2) to produce an alkane - due to the fact that the maximum number of hydrogen atoms are now attached.

Conditions:
-The reaction must be at a temperature of 150°C with a NICKEL CATALYST.

-This process of hydrogenising alkenes is used to make margarine.

Example:

Ethene + Hydrogen —> Ethane

C2H4 + H2 —> C2H6

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15
Q

How do alkenes react with water (steam)? What conditions must the reaction be under? Give an example:

A

-Alkenes make alcohols when reacted with water (steam).

Conditions:
-There must be a high temperature and a concentrated PHOSPHORIC ACID CATALYST.

  • Displayed Formula:
  • The alkene gains 2H’s and an O (H2O) from the water. So you draw an O—H as well as an H on its own, onto the hydrocarbon.

Example:

Ethene + Steam —> Ethanol

C2H4 + H2O —> C2H5OH

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16
Q

What functional group does the homologous series of alcohols contain?

A

The ‘OH’ functional group.

This helps you to recognise an alcohol.

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17
Q

What is the general formula for an alcohol?

A

(CnH2n+1)OH

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18
Q

What are the the first 4 alcohols and there chemical formula?

A

Methanol, CH3OH
Ethanol, C2H5OH
Propanol, C3H7OH
Butanol, C4H9OH

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19
Q

Which alcohol is ‘common alcohol’ used in drinks?

A

Ethanol, C2H5OH

20
Q

What does the displayed formula of an alcohol look like?

A

It looks like a hydrocarbon except on one of the branches, there is an O connected to an H:

Methanol:

         H
         | 
H — C — OH
         |
         H
21
Q

What molecules are alcohols definitely not examples of?

A

They are NOT Hydrocarbons.

They don’t have just hydrogen and carbon atoms in their bonds.

22
Q

What functional group does the homologous series of carboxylic acids contain?

A

The ‘COOH’ functional group.

23
Q

What is the general formula for carboxylic acids?

A

Cn-1H2n-1COOH (or CnH2nO2)

E.g Ethanoic Acid = 1C, 3H + COOH gives you CH3COOH.

24
Q

What are the first 4 carboxylic acids and what are there chemical formulas?

A

Methanoic Acid, HCOOH (CH2O2)

Ethanoic Acid, CH3COOH

Propanoic Acid, CH3CH2COOH

Butanoic Acid, CH3CH2CH2COOH

*Essentially you start with HCOOH (CH2O2), and you add CH3. Then you add CH2 each time.

25
Q

What carboxylic acid is the main acid in vinegar?

A

Ethanoic Acid, CH3COOH

26
Q

What is an Ester? How is an Ester formed?

A

An Ester is a chemical compound derived from an acid.

An Ester is formed if you replace the H in the ‘COOH’ of a carboxylic acid with a hydrocarbon.

27
Q

What functional group does an Ester contain?

A

The ‘COO’ functional group.

28
Q

What is one example of an Ester?

A

Ethyl Ethanoate, CH3COOCH2CH3 (C4H8O2)

29
Q

How do you draw the displayed formula of ethyl ethanoate?

A

The chemical formula is CH3COOCH2CH3. Move from left to right.

         H     
         |      
H — C — C == O   H     H
         |        \           |      |
         H          O  — C — C — H
                                |      |
                                H     H

Here you can see methane (CH3), connected to a (COO) which then branches off with a (CH2) and a (CH3).

30
Q

What are the 2 methods of making common alcohol (ethanol)?

A

1) Industry: Reacting ethene with steam (+ a phosphoric acid catalyst).
2) Lab: Fermenting sugars (e.g glucose) from plants with yeast:

C6H12O6 (+yeast catalyst) —> 2C2H5OH + 2CO2

31
Q

How does ethanol (common alcohol) burn/combust? What do alcohols burning produce?

A

Ethanol burns completely and well in air with a ‘clean blue flame’. (Think christmas pudding), and produces Carbon Dioxide and Water.

Ethanol + Oxygen —> Carbon Dioxide and Water

C2H5OH + 3O2 —> 2CO2 + 3H2O

*This is oxidation by combustion.

32
Q

How can the combustion of ethanol be used?

A

Ethanol can be used as an alternative fuel to petrol and diesel.

It is classed as a type of BIOFUEL.

33
Q

How do alcohols react with sodium?

A

When an alcohol reacts with sodium metal, it forms a solution of:

  • a sodium alkoxide (e.g sodium methoxide/sodium ethoxide)
  • hydrogen gas

E.g Sodium + Ethanol —> Sodium Ethanoxide + Hydrogen

The solution effervesces (fizzes/gives off bubbles) as hydrogen is produced.

34
Q

How can ethanol be chemically oxidised (without burning)? What products are formed? How do they compare to the products from oxidation by combustion?

A

Alcohols can be chemically oxidised by:

1) CONTROLLED (naturally occuring) - reacting with chemical oxidising agents
2) UNCONTROLLED - reacting with microbes in the air.

The process produces ethanoaic acid (main acid in vinegar) and water.

E.g Ethanol + Oxidising Agents —> Ethanoic Acid + Water (don’t need to know symbol equation).

*These products are different oxidation products compared to oxidation from combusting.

35
Q

What are the 3 main uses of alchohols?

A

1) Fuels - ethanol used as a biofuel.
2) Solvents - perfumes, mouthwashes, aftershaves and cleaning products. Evaporates quicker than water. (lower boiling point).
3) Drinks - ethanol is used, all acohols are toxic but ethanol is the least toxic and can be metabolised by enzymes. (If you drank methanol, propanol or butanol - you could easily die).

36
Q

What pH range do solutions of carboxylic acids have?

A

Less than 7 (all acidic).

37
Q

Do carboxylic acids have the same typical reactions as other acids?

A

Yes

38
Q

How do carboxylic acids react with metal carbonates? *Think CAWCS

A

Metal Carbonate + (carboxylic) Acid —> Water + Carbon Dioxide + Salt

E.g Sodium Carbonate + Ethanoic Acid —> Water + Carbon Dioxide + Sodium ethanoate (salt)

39
Q

What is the main observation for a reaction between a metal carbonate and a carboxylic acid?

A

Fizzing as CO2 is given off.

40
Q

What type of acid is a carboxylic acid? Strong or Weak

A

Weak Acid

Acids like HCl are strong.

41
Q

How are acids determined as strong or weak? How do strong acids react with water VS weak acids?

A

By their reactions with water.

Strong acids: All acid molecules break down to form H+ Ions, causing violent fizzing.

Weak acids: ONLY A FRACTION of the molecules break down to form H+ ions, causing less violent fizzing.

General Formula:
Acid + Water —> H+ ions

42
Q

How would the pH value of a strong and weak acid aqueous solutions compare with the same concentration?

A

Weak acids would have a higher pH in the same concentration as they are less acidic and therefore contain less H+ ions.

*the acids are aqueous so they will always contain H+ ions. Strong = all molecules break down to form H+ ions. Weak = some of molecules break down to form H+ ions.

43
Q

How are esters made? What is the general formula for making an Ester?

A

Esters are made by reacting a carboxylic acid with an alcohol (in the presence of a sulfuric acid catalyst). Water is also produced.

Formula:
Carboxylic Acid + Alcohol (with catalyst) ⇌ Ester + Water

The reaction is reversible.

44
Q

What are the properties of Esters?

A

Esters are:

  • volatile (turn into a gas / vapourises easily)
  • fragrant - many smell sweet and fruity.
45
Q

How are esters used based on their properties?

A

Used as perfumes, fragrances and food flavourings (pears, strawberries, oranges, rasberries, bananas, apples and pineapple all contain esters).

GCSE Chemistry (17 decks)

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