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Paper 1 Chemistry
Chemical Changes
Definitions
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Cards (21)
Acid
:
Acids
produce
hydrogen
ions (
H+
) in
aqueous
solutions
pH range of
0-6
Alkali:
Alkalis
produce
hydroxide
ions (OH-) in
aqueous
solutions
pH range of
8-14
Crystallisation
:
Separation technique
to produce
solid crystals
from a
solution
by
evaporating
the
solvent
Displacement
:
A
chemical reaction
where a more
reactive element displaces
a
less reactive element
from its
compound
Electrolysis:
Splitting
up of an
ionic compound
using
electricity
Chemical reactions
occur at the
electrodes
and
materials decompose
Electrolyte:
Solution
containing free
ions
from
molten
or
dissolved
ionic substance
Ions
are free to
move
to carry
charge
Extraction
:
Techniques
used to separate a
desired substance
when
mixed
with others
Filtration
:
Separation technique
to
separate solids
from
liquids
Negative electrode
(cathode):
Electrode
where
hydrogen
is produced if the
metal
in the
electrolyte
is more
reactive
than
hydrogen
Positively charged ions gain electrons
, reactions are
reductions
Neutralisation
:
Reaction when an
acid
and a
base
react to form
water
and a
salt
Oxidation
:
Reaction
involving the
gain
of
oxygen
Loss
of
electrons
pH scale:
Measure of
acidity
or
alkalinity
of a solution from
0
to
14
Can be measured using universal
indicator
or a pH
probe
Positive
electrode (
anode
):
Electrode
where
oxygen
is produced unless the solution contains
halide
ions, then the
halogen
is produced
Negatively
charged ions
lose
electrons, reactions are
oxidations
Reduction:
Reaction
involving the
loss
of
oxygen
Gain
of
electrons
Reduction with carbon:
Metals
less reactive
than carbon can be
extracted
from their
oxides
by
reduction
with
carbon
Strong acid:
Completely ionised
in
aqueous solution
Examples:
hydrochloric
,
nitric
, and
sulfuric
acids
Reactivity series:
Metals
arranged in
order
of
reactivity
Used
to
predict products
from
reactions
Universal indicator
:
Mixture
of
dyes
that
changes color gradually
over a range of
pH
Used in
testing
for
acids
and
alkalis
Weak acid:
Partially ionised
in
aqueous solution
Examples:
ethanoic
,
citric
, and
carbonic acids
Redox reaction:
Reaction where
both oxidation
and
reduction
occur
simultaneously
Titration:
Technique
using a
solution
of
known concentration
to determine the
concentration
of an
unknown solution