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.