Acids and Bases

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Level 1: By the end of this level, you will know;

  • What a Bronsted-Lowry Acid is.
  • What a Bronsted Lowry Base is.
  • How to tell a strong acid/ base from a weak one.
  • The basics of the PH scale.

If you can remember from the land of GCSE acids and bases were quite nice little  nuggets. You know acid reacts with base to make a salt, water and if you had a carbonate Carbon Dioxide. Well A2 truns around and says let's chuck maths into this basic topic! Now don't worry about the maths yet because we still have to go through level 1, or the basic fundementals of the whole topic.

Now let's have a look at this example below:

HCl + NaOH  --> NaCl + H2O.

Now at the land of GCSE, you'd think that the HCl would donating H+ to the NaOH well this is true but in 1923 Bonsted and Lowry decided to make a wonderful defintion which would be the ultimate one for all reactions (except with we hit Lewis Acids and Bases but let's not confuse ourselves). So Bronsted and Lowry stated that acids are proton donors that release hydrogen ions when mixed with water, bases on the other hand are proton acceptors that grab hydrogen ions from water molecules when in solution.

So if we took the example above and made 2 half equations then we'd see this point:

H+ + OH- --> H2O

Cl- + Na+ --> NaCl

We also remember from the land of GCSE that different chemicals have different PH. This is the scale which measures the hydrogen ion concentration of a chemical, this varies from 1 (very strong acid) to 14 (very strong base) with 7 being neutral. So what causes use to wince slightly when we squirt lemon juice in our eye but HCl burns our skin? Well acid/base strength depends on the ability for the chemical to dissociate. A strong acid such as HCl can almost completely dissociate in water whilst a weak acid only parcially disociates. This is same logic that is applied to the strength of Bases.

Once you understand this, you can progress onto level 2. It is important to fully understand all of the concepts in level 1 before you continue otherwise you will be confused. 

Level 2: By the end of this level you will know:

- Why Water can act as an acid or

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