chemical changes Flashcards
What happens in oxidation reactions?
A substance often gains oxygen and it loses electrons.
What happens in reduction reactions?
A substance often loses oxygen and gains electrons.
How are metal oxides formed?
Metals react with oxygen to form metal oxides.
What happens when a metal reacts?
Their atoms lose electrons to form positive metal ions. The more easily an electron is lost the more reactive it is.
What is the reactivity series?
The reaction of metals with acid and water can be used to place them in order of reactivity. This is called the reactivity series.
When metals react with acids what is produced?
Metal salts and hydrogen.
What happens in a displacement reaction?
A more reactive metal will displace a less reactive metal from a solution of its salt.
Eg magnesium + copper sulfate = copper + magnesium sulfate.
What are metals more reactive than carbon extracted by?
Extracted from molten compounds in electrolysis.
OILRIG
Oxygen is the loss of electrons.
Reduction is the gain of electrons.
What happens to substances dissolved in water?
They dissociate into their individual ions.
Acid + metal hydroxide =?
Salt + Water
What do acids and alkalis contain?
Acids contain hydrogen ions H+ (aq)
Alkalis contain hydroxide ions OH- (aq)
H+ (aq) + OH- (aq) =?
H20(l)
acid + metal oxide =?
Acid + metal carbonate=?
salt + water
salt+ water + carbon dioxide
What salts do hydrochloric, nitric and sulfuric acid produce?
Hydrochloric acid produces chloride salts.
Nitric acid produces nitrate salts.
Sulfuric acid produces sulfuric salts.
(RP) Preparation of a pure, dry sample of soluble salt from an insoluble oxide or carbonate.
1) Add the metal oxide or carbonate to a warm solution of acid until no more will react.
2) Filter the excess metal oxide or carbonate to leave a solution of the salt.
3) Gently warm the salt solution so that the water evaporates and crystals of salt are formed.
What happens to weak and strong acids in water?
Strong acids are completely ionised (split up into ions) in water.
Weak acids are only partially ionised in water.
What is electrolysis?
It is the use of an electrical current to break down compounds containing ions into their elements.
What are electrodes and electrolytes?
Electrodes are made from solids and conduct electricity.
Electrolytes is the substance being broken down.
What happens during electrolysis?
-Negatively charged ions move the anode (positive electrode
-Positively charged ions move to the cathode (negative electrode).
What does cryolite do?
It lowers the melting point of aluminium oxide meaning less energy is needed making it cheaper.
When is hydrogen produced?
It is produced at the cathode if the metal is more reactive than hydrogen. (Potassium Sodium lithium Calcium
Magnesium Aluminium Zinc Iron.
Where will the halogen be produced if the aqueous solution contains halide ions?
At the anode.
