WJEC Chemistry 3 Revision

Pretty much all you need to know for higher tier C3. The notes are somewhat shortened so if there are any concerns don't hesitate to contact me (:

HideShow resource information
  • Created by: Lewis
  • Created on: 25-04-11 13:03
Preview of WJEC Chemistry 3 Revision

First 320 words of the document:

The Contact Process
The contact process is the industrial manufacture of sulphuric acid.
Stage One: Sulphur is burned in air to form sulphur dioxide.
S + O2 SO2
Stage Two: Sulphur dioxide is reacted with more oxygen. This requires a Vanadium (V) Oxide catalyst
and a temperature of 450°C to ensure that the reaction occurs quickly.
2SO2 + O2 2SO3 (sulphur trioxide)
Stage 3: Sulphur trioxide is absorbed into concentrated sulphuric acid (98%) and then watered down.
SO3 + H2SO4 H2S2O7 (oleum)
H2S2O7 + H2O H2SO4
Alternatively, sulphur trioxide could be reacted with water to form sulphuric acid, however, the
reaction is highly exothermic and produces sulphuric acid gas which is highly corrosive and very
difficult to condense back to a liquid, as well as being difficult to contain.
SO3 + H2O H2SO4 + danger!
Sulphuric acid is widely used in the chemical industry as a dehydrating agent. It will readily remove
oxygen, even from your skin.
In the experiment where sulphuric acid is added to glucose, the sulphuric removes the hydrogen and
oxygen from the glucose which leaves steam and carbon.
Glucose Carbon + Steam
C6H12O6 6C + 6H2O
Acids and Bases
Acids are proton (H+) donors.
HCl + H2O H3O+ (hydronium ion) + Cl-
Strong Acids
Strong acids completely dissociate into ions.
HCl H+ + Cl-
Weak Acids
These don't completely dissociate into ions.
CH3COOH (ethanoic acid) CH3COO- + H+
Bases are proton (H+) acceptors.
NH3 + H2O NH4 + OH-
Alkalis are soluble bases. Not all bases can dissolve in water, therefore not all bases are alkali, but all
alkalis are bases.
Strong Bases
Strong bases completely dissociate into ions.
NaOH Na+ + OH-
Weak Bases

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Weak bases don't completely dissociate into ions.
This is the reaction between an acid and a base to form a salt and water.
NaOH +HCl NaCl + H2O
PH Scale
A scale of number between 0 and 14 showing different PH values of acids and bases. The PH of acid
or base depends upon the strength of the acid or base.…read more

Page 3

Preview of page 3

Here's a taster:

Pentane Methyl Butane Di-Methyl Propane
All alkenes are made up of carbon and hydrogen, and all contain at least one carbon to carbon double
bond, represented by C=C. Alkenes are said to be unsaturated because their double bond can open
up and let other atoms join on. They have the general formula CnH2n.
Ethene - C2H4 Butene ­ C4H8 Pentene ­ C5H10
How can we distinguish between alkanes and alkenes?
Add an alkane or alkene to bromine water.…read more

Page 4

Preview of page 4

Here's a taster:

All alcohols contain the functional group (-OH).
Methanol ­ CH3OH Ethanol ­ C2H5OH Propanol ­ C3H7OH
Making Alcohols
Alcohol is made by the fermentation of sugar by the enzymes in yeast.
Glucose Ethanol + Carbon Dioxide
C6H12O6 2C2H5OH + 2CO2
Advantages of Alcohols
o Some people like the taste.
o It is used as a fuel
o The alcohol industry creates jobs and some prosperity.
o It can be a social catalyst.
o It is used in medicine.
o It is good solvent (evaporates quickly).…read more

Page 5

Preview of page 5

Here's a taster:

The UK has a somewhat dreary and cold climate, whereas sugar cane (where ethanol comes from
naturally) requires a hot and sunny climate to be grown. Also, there is not enough land available to
grow enough sugar cane to produce fuel for the whole county.
What Happens When Wine Is Uncorked For a Few Days?
Microbial oxidisation occurs, whereby microbes in the air respire in the wine, thus using up
oxygen and thus converting the ethanol to ethanoic acid, the acid found in vinegar.…read more

Page 6

Preview of page 6

Here's a taster:

We can test for the ammonium ion by adding sodium hydroxide to ammonium chloride and
heating gently. Ammonium gas will be given off, and this gas will turn damp red litmus paper
We can test for the sulphate ion by adding barium chloride solution, if sulphate is present,
then the solution will turn into a thick white precipitate.
We can test for the carbonate ion by adding an acid to it; it will fizz and give off carbon
dioxide.…read more

Page 7

Preview of page 7

Here's a taster:

N = 0.1× 0.025 (*always remember to divide your concentrations by one thousand to covert
to decimetres)
N = 0.0025 moles
There is a 1:1 ration between NaCl and HCl, therefore the number of moles of NaCl = 0.0025
From this, we can work out the concentration;
C = 0.0025 ÷ 0.0225 (remember to divide volume by one thousand!)
C = 0.…read more


Mariya Onatska


Similar Chemistry resources:

See all Chemistry resources »See all resources »