AS level Chemistry
OCR (Chemistry A – H032, H432)
Acids and Redox
Includes:
Acids
Bases
Neutralisations
Titrations
Preparing standards
Acid-base titration method
Redox
, Acids
Definition
Acids: A species that releases H+ ions into aqueous solution.
Strong Acid: An acid that dissociates completely in solution.
Weak Acid: An acid that dissociates partially in solution.
Common acids that you will have come across already through science are:
Hydrochloric Acid HCl
Sulphuric Acid H2SO4
Nitric Acid HNO3
Phosphoric Acid H3PO4
Ethanoic Acid (vinegar) CH3COOH
When an acid dissociates the H+ is left in the solution:
HCl (aq) H+ (aq) + Cl- (aq)
H2SO4 (aq) 2H+ (aq) + SO42- (aq)
Water in the solution is always in excess.
Acids can come with different strengths: strong and weak.
Strong acids, like the 2 examples above, the H+ completely dissociates.
Weak acids, like in the example below, however only partially dissociates in a
solution. This means only a small amount of the H+ ions in the compound are
separated.
CH3COOH (aq) H+ (aq) + CH3COO- (aq)
The equilibrium symbol is used as the reaction is not complete, and there is both a
forward and a backward reaction.
There are 4 possible hydrogen atoms that could dissociate from the ethanoic acid,
however only 1 does, and this also does not happen in all ethanoic acid compounds.
OCR (Chemistry A – H032, H432)
Acids and Redox
Includes:
Acids
Bases
Neutralisations
Titrations
Preparing standards
Acid-base titration method
Redox
, Acids
Definition
Acids: A species that releases H+ ions into aqueous solution.
Strong Acid: An acid that dissociates completely in solution.
Weak Acid: An acid that dissociates partially in solution.
Common acids that you will have come across already through science are:
Hydrochloric Acid HCl
Sulphuric Acid H2SO4
Nitric Acid HNO3
Phosphoric Acid H3PO4
Ethanoic Acid (vinegar) CH3COOH
When an acid dissociates the H+ is left in the solution:
HCl (aq) H+ (aq) + Cl- (aq)
H2SO4 (aq) 2H+ (aq) + SO42- (aq)
Water in the solution is always in excess.
Acids can come with different strengths: strong and weak.
Strong acids, like the 2 examples above, the H+ completely dissociates.
Weak acids, like in the example below, however only partially dissociates in a
solution. This means only a small amount of the H+ ions in the compound are
separated.
CH3COOH (aq) H+ (aq) + CH3COO- (aq)
The equilibrium symbol is used as the reaction is not complete, and there is both a
forward and a backward reaction.
There are 4 possible hydrogen atoms that could dissociate from the ethanoic acid,
however only 1 does, and this also does not happen in all ethanoic acid compounds.
