Chemistry P1 - Chemical Changes Flashcards
Which two reactions are examples of oxidisation?
- sodium carbonate —-> sodium oxide + carbon dioxide
- magnesium + oxygen —-> magnesium oxide
- mercury oxide —-> mercury + oxygen
- zinc + oxygen —-> zinc(II) oxide
- magnesium + oxygen —-> magnesium oxide
- zinc + oxygen —-> zinc(II) oxide
Metals react with oxygen to produce metal _______
This reaction is called ______
- oxides
- oxidation
What are the products of the reaction of potassium with water?
potassium hydroxide + hydrogen
_______ + sulfuric acid —-> magnesium sulfate + ________
magnesium
hydrogen
List the reactivity series
Potassium
Sodium
Calcium
Magnesium
Aluminium
CARBON
Zinc
Iron
Tin (Sn)
Lead (Pb)
HYDROGEN
Copper (Cu)
Mercury (Hg)
Silver (Ag)
Gold (Au)
What are electrodes in electrolysis?
Solid conductors (metal or carbon)
What is an electrolyte in electrolysis?
The liquid or solution that contains and ionic compound (ions are free to move)
What do you have to do if the electrolyte is soluble?
Nothing
What do you have to do if the electrolyte is insoluble?
- Melt it (why?)
- So the ions are free to move
What is the positive electrode called?
The anode
What is the negative electrode called?
The cathode
What must be connected to the anode and cathode and why?
A wire (so electrons can flow) connected to a power supply (to drive the flow of electrons)
What does the word electrolysis mean
Splitting up with electricity
Which electrode will a negative ion be attracted to and what will it become?
- The anode
- Charged ion (-) —-> neutral atom
Which electrode will a positive ion be attracted to and what will it become?
- The cathode
- Charged ion (+) —-> neutral atom
Has a negative ion gained or lost electrons?
Gained
Has a positive ion gained or lost electrons?
Lost
Which two of the following chemical processes are used to extract metals from their ores?
- Thermal decomposition
- Electrolysis
- Reduction with carbon
- Electrolysis
- Reduction with carbon
What do elements have to be to be able to be reduced with carbon?
Less reactive than carbon
How do you extract metals that are more reactive than carbon
Electrolysis
How do you extract metals that are less reactive than carbon
Reduction with carbon
Why wouldn’t you want to use electrolysis?
- Uses lots of energy
- Expensive
What does electrolysis do?
Separate ionic compounds into their pure elements
What is aluminium found as in the earth?
Bauxite (aluminium oxide)
Why do we mix aluminium oxide with cryolite before electrolysis?
Because it lower s the melting point
What charge will a metal ion always have?
Positive
What charge do metal and non-metal ions have in an ionic compound?
Metal - positive (loses electrons)
Non-Metal - negative (gain electrons)
What will happen to the metal ion in electrolysis?
It will collect at the cathode as a solid/liquid
What will happen to the NON-metal ion in electrolysis?
It will collect at the anode and escape as a gas
Which elements for diatomic molecules? (at the anode)
Hydrogen, Nitrogen, Flourine, Oxygen, Iodine, Chlorine, Bromine
Have no fear of ice cold bear
What does OIL RIG mean?
Oxidation Is Loss (of electrons)
Reduction Is Gain (of electrons)
What are most metal oxides?
Insoluble
What is the rule for whether the H^+ ion or the metal^+ ion will be discharged at the cathode in an aqueous solution?
The ion of the least reactive element will be discharged
What is the rule for what ion is discharged at the anode?
- If a halide is present it is discharged
- If a halide is not present, the hydroxide is discharged
What would be discharged at the anode and cathode if the electrolyte was NaCl (aq)?
Cathode - Hydrogen (Na is more reactive)
Anode - Cl (It is a halide)
