C4 chemical changes Flashcards
Oxidation
Metal gains oxygen
Loses electrons to make positive ions
Electrons transferred to oxygen atom to make negative ions
Basic oxide formed
Reduction
Loses oxygen
Gains electrons
Most abundant element in earths crust
Oxygen
Silicon
Aluminium oxide
Iron 3 oxide
Reactivity with water and dilute acids
Potassium Sodium Lithium Calcium Magnesium Zinc Iron Copper
Positive ions
First 8 in reactivity series form positive ions
The harder it is to from a positive ion the more reactive it is
Reactivity series
Potassium Sodium Calcium Magnesium Aluminium Carbon Zinc Iron Tin Lead Hydrogen Copper Silver Gold Platinum
Displacement reaction
When 2 metals react the more reactive metal displaces/ pushes out the less reactive metal
Reduction uses
Used to extract metals from their ores
Ores
A naturally occurring solid material from which a metal or valuable mineral can be extracted profitably by electrolysis
Making salts
Acids react with metals to produce salts and hydrogen
To make a crystallised salt
Add excess of substance to acid
Solution needs to be filtered into a crystallising dish
Solution needs to be concentrated by evaporation
Solution then left to evaporate, to crystallise
Redox reaction
Both oxidation and reduction occur at the same time
Bases
Metal oxides and metal hydroxides
If solvable in water alkalis
Lower concentration of H+ ions
Neutralisation
Acid+base}salt+water
Required practical- preparing a pure,dry sample of a soluble salt from an insoluble oxide or carbonate
Warm up some acid
Put in powdered metal/base in excess
Filter solution into evaporating dish
Heat till it starts to spit then leave to evaporate and crystallise