Chemical Changes Flashcards
What is the formula for hydrochloric acid?
HCl
What is the formula for nitric acid?
HNO₃
What is the formula for sulfuric acid?
H₂SO₄
What makes an acid strong?
Fully ionising in a solution.
What is the main laboratory base?
Sodium hydroxide
What does caustic mean?
Can burn skin and damage materials
What are alkalis
Soluable bases
What is the general equation for neutralisation?
Acid + base ➝ salt and water
What does pH mesure?
The number of H⁺ ions in a solution
How much does the concentration of H⁺ ions need to be reduced to change pH by 1 unit?
Decreased by a factor of 10.
What is oxidation
- Gaining oxygen
- Loosing electrons
What is reduction?
- Loosing oxygen
- Gaining electrons
What is a displacement reaction?
Where a more reactive element takes the place of a less reactive one in a compound.
What is an ore?
A rock with enough metal compound in it to make it worth extracting
How can metals less reactive than carbon be extracted from their ores?
Reduction with carbon.
This forms the metal and carbon dioxide.
Acid + base ➝ ______ + ______
salt + water
Acid + metal ➝ ______ + ______
salt + hydrogen
Acid + metal oxide ➝ ______ + ______
salt + water
Acid + metal carbonate ➝ ______ + ______ + _____
salt + water + carbon dioxide
What chemicals can be separated using electrolysis?
Ionic compounds
What is the cathode?
The negative electrode
What is the anode?
The positive electrode
What is a cation?
A positive ion which moves to the cathode.
What is an anion?
A negative ion which move to the anode.
What is the electrolyte?
An ionic substance, which is ether molten or in a solution.
What is aluminium ore called?
Bauxite.
What is the chemical formula for aluminium ore?
Al₂O₃
What is put into the solution with aluminium ore for electrolysis, and why?
Molten cryolite.
This reduces the melting point to save energy and money.
What is cryolite?
An aluminium based compound.
Why do the anodes need to be replaced regularly in the extraction of aluminium ore?
They are made from graphite, so the oxygen produced reacts with the carbon in the anodes.
What is the rule for the products at the cathode for aqueous solutions?
Hydrogen is produced unless the metal is less reactive than hydrogen.
What is the rule for the products at the anode for aqueous solutions?
Oxygen is formed unless there is a halide ion.
How is an electrochemical cell made?
Connecting two different metals in contact with an electrolyte, the reaction between the electrodes and the electrolyte generates electricity?
Is the reaction between the electrodes and electrolyte in a cell exothermic or endothermic?
Exothermic.
Which metal acts as the anode in a cell?
The metal that is more reeactie.
How does the types of metals effect the voltage generated in a cell?
The bigger the difference in their reactivity
the greater the voltage produced.
What happen if the same metal is used for both electrodes in a chemical cell?
0 volts are produced, as their reactivity is the same.
What 3 factors effect the voltage generated by a battery?
- Type of metals used
- Type of electrolyte
- How many cells are joined together
What is a battery?
Many cells joined together.
How are batterys recharged?
Recharging a battery reverses the reaction so it can be used again.
What is a fuel cell?
An electrical cell which uses fuel (hydrogen) and oxygen to release energy in a reaction
which is transferred to electrical energy.
How is hydrogen stored?
In pressurised containers.
