a base is any compound that can neutralise an acid
Examples:
metal oxide - copper oxide
metal hydroxide - sodium hydroxide
metal carbonates - magnesium carbonate
metal hydrogen - calcium hydrogen
ammonia
Acid + base -------- salt + water
sulphuric acid + copper oxide -------- copper sulphate + water
warm the acid + base
then when it is cool,
filter the mixture. boil
the filtrate and leave
the remaining solution
in a petri dish the
water will evaporate
and leave salt crystals
behind
Making salts - acid plus carbonate
acid + carbonate -------- salt + carbon dioxide + water
keep adding the
magnesium carbonate
until no more fizzing
occurs. filter out the
remaining powder that
has not reacted, pour
it into a petri dish and
leave it to evaporate.
long thin salt crystals
of will form and be left
in the petri dish.
Action of Acid on metals
to test the effect of hydrochloric acid and sulphuric acid on 4 different metals
Iron
Copper
Zinc
Magnesium
Sulphuric acid
created more
hydrogen than the
hydrochloric acid.
produced heat with magnesium
Hydrochloric acid
produced heat with magnesium
the most reactive metals produce hydrogen
with this information we can make a reactive series
leave the metal in a test
tube full of the acid until
a further reaction has
finished. when it is
heated gently (bunsen
flame) salt crystals will
form and give off the gas
hydrogen
all acids react in the same way when they are tested in these ways
action with magnesium: fizzing, turning milky
action with copper oxide: strong fizzing, turned blue
action with magnesium carbonate: fizzing, turning milky
pH: red (1)
Rusting of Iron
rusting is the oxidation of iron to form iron oxide
this reaction occurs slowly in damp air
iron + oxygen + water vapour -------- iron oxide (rust)
when water and oxygen are present rusting occurs
when oxygen and/or water is removed, the rusting is reduced
Extraction of Copper
all of the copper on the earths crust is found as copper compounds or ores.
one of the copper ores is malachite. there are three stages in extracting the copper from malachite.
when it is heated, carbon dioxide will be let out - keep reacting
until no more carbon dioxide is produced
black copper oxide and carbon dioxide gas were formed.
STAGE 2
change the copper oxide into copper sulphate
copper oxide is a base. it dissolves in
an acid to make a neutral solution that
contains a salt.
acid + base -------- salt + water
sulphuric acid + copper oxide -------- copper sulphate + water
heat the mixture of copper oxide and
sulphuric acid until it reaches 70 oC
and then filter off the unreacted copper
oxide and keep the copper sulphate
solution to use in stage 3.
heating the copper oxide
withe the sulphuric acid
formed the blue copper
sulphate solution. the excess
copper oxide was removed
by filtration
STAGE 3
remove the copper from the copper sulphate
compounds can be broken down using electricity
(electrolysis)
when copper sulphate is electrolysed,
it breaks down to form copper metal,
sulphuric acid and oxygen