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GCSE Chemistry
Paper 1
Chemical Changes
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Cards (33)
What is Oxidation?
Substance gains
oxygen
What is reduction?
Substance loses
oxygen
When reacted with water :
What do Group 1 metals make ?
Metal
hydroxide
+
Hydrogen
What elements have no reaction with water?
Magnesium
,
Zinc
,
Iron
&
Copper
What do you have to react the Group 1 elements that do not react with water with instead?
Dilute acid
O xidation
I s
L ost
R
eduction
I s
G
ained
How do you extract Unreactive metals?
Found in
earths
surface
How can metals which are less reactive than Carbon be extracted ?
By
reduction
of Carbon
Acid
+
metal
--->
Salt
+
Hydrogen
Are acids H+ or OH- ?
H+
What is neutralisation?
Acids
being neutralised by
alkali
and
bases
.
Acid
+
Metal oxide
--->
Salt
+
Water
Acid
+ Metal carbonate ---> Salt + Water +
CO2
How are soluable salts made?
Made from
acids
by reacting them with solid
insoluable
substances
OH- in terms of pH scale :
Alkaline
H+ in terms of pH scale :
Acid
What are Titrations used for ?
Used to measure volumes of
acid
&
alkali
solutions that react with eachother
What is a strong acid in terms of Ionisation?
Completely
Ionised
Examples of
Strong Acids
:
Hydrochloric
Nitric
Sulfuric
What is a weak acid in terms of Ionisation?
Partially ionised
Examples of
Weak Acids
:
Ethanoic
Citric
The stronger
acid
, the lower the
pH
.
As
pH scale
decreases by 1 unit,
Conc
of
H+
ions increases by 10x
What is Electrolysis?
Use of
electronic
current to break down
compounds
containing
ions
into consistuent
elements
What is the Electrolyte?
Substance used to break down, able to conduct electricity
+
Ions
move to
cathode
--
ions
move to
Anode
Why is
Electrolysis
expensive?
Melting
compounds
requires a lot of energy
Lots of energy required to produce
electrical
current
Metal
produced at
Cathode
Non-metals
produced at
Anode
Electrolysis in Aqueous solutions :
+
electrode
= Hydrogen produced if more reactive than
hydrogen
-- electrode = oxygen produced unless solution contains halide ions
Why at - electron is oxygen produced unless solution contains halide ions?
H2O
molecules break down producing H ions and hydroxide ions are discharged.
What does Cryolite do?
Lowers
melting point