Topic 4: Chemical Changes Flashcards
What ions do acids form when they dissolve in water (an aqueous solution)?
Hydrogen ions (H+)
What ions do alkalis form when they dissolve in water (an aqueous solution)?
Hydroxide ions (OH-)
What does a pH scale measure?
How acidic or Alkaline a substance is.
What does an oxidation reaction involve?
Gaining oxygen and losing electrons
What does a reduction reaction involve?
Losing oxygen and gaining electrons
When a substance is oxidised, it always…
…Loses electrons
When a substance is reduced, it always…
…Gains electrons
What is OILRIG?
Oxidation
Is
Loss
Reduction
Is
Gain
What happens in a displacement reaction?
A more reactive metal (one that forms positive ions more easing) removes a less reactive metal from a compound.
A metal can only displays above metal from a compound if it is located _______ it in the reactivity series
Above.
What can more reactive substances do in a displacement reaction?
They can replace less reactive substances from compounds.
Complete this displacement reaction:
Sodium Bromide + Chlorine -> ? + ?
Sodium Bromide + Chlorine -> Sodium Chloride + Bromine
Bromide ions are oxidised (electrons are lost)
2Br- ->Br2 + 2e-
Chlorine is reduced (electrons are gained)
Cl2 +2e- -> 2Cl-
Sodium remains unchanged as it is a spectator ion in this reaction.
What is a spectator ion?
Ions that remain unchanged in the reaction.
When reacting with other substances, metal atoms always form….
Positive ions
What is the reactivity of a metal linked to?
How easy it is for a metal to form it’s positive ion.
How can metals be arranged?
In order of reactivity.
What are native metals?
Metals that are found in the Earth’s crust as pure metals that are highly unreactive.
Name 2 examples of native metals.
Gold and Platinum, which are both highly UNREACTIVE.
What charge do ions normally get from metal atoms?
A positive charge.
What charge ions normally form from metal atoms?
Positive ions
What 3 metals all react quickly with cold water to produce metal hydroxide + Hydrogen gas?
Potassium, sodium and lithium
(in ascending order)
What colour flame is produced when potassium reacts with water?
A lilac flame.
What do metals react with dilute acid to give?
a salt and hydrogen gas
Name 5 examples of metals that react with dilute acids but not with cold water?
Magnesium
Aluminium
Zinc
Iron
Lead
Name 4 metals that are not reactive enough to react with dilute acids.
(think jewellery)
Copper
Silver
Gold
Platinum
Metal + Water =
Metal + Water -> Metal Hydroxide + Hydrogen
Metal + Dilute Acid =
Metal + Dilute Acid -> A Salt + Hydrogen
Name 2 reasons why carbon is used to extract many metals.
Cheap
Abundant
In what conditions does reducing a metal with carbon will extract the metal?
the metal has to be lower in the reactivity series than carbon.
How is carbon used to extract metals?
in reduction, metal uses oxygen to form a pure metal, which is done by heating the metal oxide with the presence of carbon, usually coal.
What is always formed when acids react with metals?
Hydrogen and a salt
Magnesium + Hydrochloric Acid =
Magnesium + Hydrochloric Acid -> magnesium chloride + hydrogen
Zinc + Sulfuric Acid =
Zinc + Sulfuric Acid -> Zinc Sulfate + Hydrogen
What 2 reactions do redox reactions involve?
Oxidation and Reduction.
Are spectator ions included in the ionic equation?
No.
how are acids neutralised?
by reacting them with bases (an alkali is a based that dissolves by water)
what do acid + metal carbonate make?
a salt + water + CO2
hydrochloric acid + calcium carbonate ->
-> calcium chloride + water + CO2
Acid + metal oxide ->
-> a salt + water
acid + hydroxide ->
-> a salt + water
hydrochloric acid + magnesium oxide ->
-> magnesium chloride + water
hydrochloric acid + sodium hydroxide ->
-> sodium chloride + water
what are soluble salts?
salts that dissolve in water
how do we produce soluble salts?
by reacting an acid and a solid insoluble substance (such as a pure metal, metal carbonates etc.)
How are blue copper sulfate crystals formed?
By adding black copper oxide to sulfuric acid
DID NOT DO RP
