Electrolysis, metals and equilibrium 1 Flashcards
Reversible reactions
Products react to form reactants
Where does dynamic equilibrium occur
In a closed system where there’s no loss of reactants or products
Dynamic equilibrium
The forwards and backwards reaction are still occurring but percentages of reactants and products are no longer changing
Why can’t dynamic equilibrium be achieved in an open system ?
Gases could escape and equilibrium can’t be achieved
How to manufacture ammonia
By the Haber process
Involves the reversible reaction between nitrogen (from the air) and hydrogen from natural gas that can reach a dynamic equilibrium.
What are the conditions in the haber process to favour the forward reaction?
450 degrees
Pressure of 200 atmospheres
Iron catalyst
How can the equilibrium position be altered
By changing the concentration, pressure or temperature
What does increasing temp do
Equilibrium position shifts in the endothermic direction
Transfers energy from the surroundings, cooling them down
What does decreasing temp do
Equilibrium position shifts in the exothermic direction
Transferring energy to the surroundings heating them up
Is the forward reaction endo or exothermic
So what’s the backwards reaction
Exothermic
Backwards is endothermic
What does increasing and decreasing gas pressure do?
Increasing- equilibrium position shifts in the direction that forms fewer gas molecules as this reduces pressure.
Decreasing- equilibrium position shifts in the direction that forms more gas molecules as this increases pressure.
What does increasing and decreasing a concentration do
Increasing- equilibrium position shifts in the direction that uses up the substance that’s been added.
Decreasing- equilibrium position shifts in the direction that forms more of the substance that’s been removed.
What happens to copper in electrolysis of copper sulphate
Copper is less reactive than hydrogen so will be produced at the cathode (+ cathode gains mass)
What is produced at the anode in electrolysis of copper sulphate
Oxygen and water
What is produced at the cathode in electrolysis of copper sulphate
Copper
What is usually used as an electrode and why
Platinum or graphite because they’re inert (unreactive)
What’s the half equation for the cathode in electrolysis of copper sulphate
Cu2+2e- = (reduction)Cu
Copper ions are gaining 2 electrons to for copper atoms
What’s the half equation for the anode in electrolysis of copper sulphate
4OH- = (oxidation)O2+2H2O + 4e-
4 hydroxide ions react to form oxygen gas and water losing 4 electrons.
The metals that react with cold water form
Hydrogen and a metal hydroxide solution
Metals that react with steam form
Hydrogen and a solid metal oxide
The metals that react with dilute acids form…
And what will be seen
Hydrogen and a salt solution
Bubbles- more depending on the reactivity of the metal
Advantages of recycling metals
Natural reserves of metal ores will last longer
Need to mine ores is reduced (reducing noise and pollution)
Less pollution (sulphur dioxide when sulphur is extracted from metal sulphide ore)
Less energy needed to recycle than to extract new metal
Less waste metal in landfill sites
Disadvantages of recycling metals
Expensive to collect, transport and sort metals
Can use more energy than mining new ores
Life cycle assessment stages
Obtaining and processing raw materials
Manufacturing and packaging products
Using product
Disposing of product
What are cations and which electrode are they attracted to
Cations are positive ions and are attracted to the negative cathode
What are anions and which electrode are they attracted to
Anions are negative ions and are attracted to the positive anode
