Chapter 4 - Acids and Redox (MODULE 2) Flashcards
what is released when acids dissolve in water
H+ ions
What is a strong acid
one which releases all its H+ ions into solution and completely dissociates in aqueous solution
What is a weak acid
one which doesn’t release all its H+ ions into solution and partially dissociates in aqueous solution
WHat are some examples of strong acids
HCl. H2SO4, HNO3
What are some examples of weak acids
ethanoic acid, most organic acids
What sign is used to indicate the forward reaction is incomplete
equilibrium arrow
What are some general examples of bases
metal oxides, metal hydroxides, metal carbonates and ammonia
what is the reaction between an acid and base called
- what is always produced
neutralisation
- a salt
What is an alkali
a base that dissolves in water releasing OH- ions into solution
How is a salt formed in neutralisation
H+ ion in acid is replaced by metal or ammonium ions from base
What are the general products for acid + metal
salt + hydrogen
What are the general products for acid + metal oxide
salt + water
What are the general products for acid + metal hydroxide
salt + water
What are the general products for acid + metal carbonate
salt + water + carbon dioxide
What is a titration used for
accurately measuring the volume of one solution that reacts exactly with another solution
What are the 3 main uses of titrations
- finding the concentration of a solution
- identification of unknown chemicals
- finding the purity of a substance
What is a standard solution
a solution of known concentration
What are standard solutions made in
volumetric flasks
what are the typical tolerances of:
- 100cm^3
- 250cm^3
volumetric flasks
- ±0.20cm^3
- ±0.30cm^3
in an acid - base titration, what measuring apparatus is used
pipette and burette
what are the typical tolerances of
- 10cm^3 pipette
- 25cm^3 pipette
- 50cm^3 burette
- ± 0.04cm^3
- ± 0.06cm^3
- ± 0.10cm^3
How are burettes always read
- from the bottom of the meniscus
- to the nearest half-division (0.05cm^3)
- always 2 d.p.
How do you calculate the mean titre
work out the mean of 2 concordant titres
what are concordant titres
titres within 0.10cm^3 of each other