Topic 4 - Extracting Metals and Equilibria Flashcards
Identify which element has been oxidise in the following reaction:
CuO + H2 -> Cu + H20
H2
Because Calcium is more reactive than copper, which is more easily oxidised?
Calcium
How do metals react with water?
Metal + Water -> Metal Hydoxide + Hydrogen
Would Silver displace iron from iron chloride solution?
No, as Silver is not as reactive as iron
Lithium sits between sodium and calcium in the reactivity series
State whether lithium would displace zinc from zinc sulfate solution and explain your answer?
Yes as lithium is more reactive than zinc
What is a metal ore?
A rock which contains enough metal to make it economically worthwhile extracting the metal from it
What are most ores located?
In the Earth’s crust
How is carbon used in extraction of metals?
It removes the oxygen
State the equation of iron oxide being added to carbon?
Iron Oxide + Carbon -> Iron + Carbon Dioxide
How would you extract tin from its metal ore? Explain your answer
Tin is less reactive than carbon so you could extract tin from its ore by reducing it with carbon
Write a balanced chemical equation for the reaction between zinc oxide and carbon?
Zinc Oxide + Carbon -> Zinc + Carbon Dioxide
2ZnO + C -> 2Zn + CO2
What metals are electrolysed?
Metals more reactive than carbon
What goes to the cathode?
The metal
What goes to the anode?
The non-metal
Al2O3 is electrolysed
State the ionic equations for the products?
Al3+ + 3e- -> Al
2O2- - 4e- -> O2
What is the disadvantage of electrolysis?
Expensive to melt/dissolve and get electricity
What is bioleaching?
Bacteria is used to separate metals from their ores, where the bacteria get energy from the bonds between the atoms
What is phytoextraction?
Growing plants in soil that contains metal compounds that they cannot use so they simply get stored in their leaves. The leaves can then be harvested.
What would be more expensive to extract, iron or aluminium?
Aluminium because it requires electrolysis which is more much expensive than reducing with carbon
What does recycling conserve?
Resources and energy
What are the disadvantages of extracting metals?
Mines are damaging and destroy habitats they are also an eye sore
Explain how a metal’s relative resistance to oxidation is related
to its position in the reactivity series?
Because metal reactivity is how easily an electron is lost and resistance to oxidation is how resistant an atom is to oxidisng both mean the same thing
What are unreactive metals found as?
Uncombined elements
What does the extraction of metals involve?
The reduction of ores
What are the disadvantages of landfill?
Takes up space and pollutes the surroundings
Which is often cheaper? Extracting metals or recycling?
Recycling
What are the advantages to recycling?
Creates jobs
Reduces landfill and mines
Material X is a metal. To recycle material X you need 110% of the energy used to extract and refine it
Explain why it might still be better to recycle material X
Disposed of metals will be put in landfill which takes up space and pollutes the surroundings
Metals are non-renewable, so recycling metals is important to conserve finite resources of the metal
What does LCA stand for?
Life cycle assessment
What does LCA involve?
The effect on the environment of obtaining the
raw materials, manufacturing the product, using the product
and disposing of the product when it is no longer useful
What stages are part of the LCA?
Obtaining the materials
Making the product
Using the product
Disposing the product
What is a reversible reaction?
A reaction where the products can react with each other to produce the original reactants
Give an example of the reversible reaction
The haber process
State the ‘equation’ for a reversible reaction
A + B ⇌ C + D
What are the conditions for the haber process?
Temperature of 450 °C
Pressure of 200 atmospheres
An iron catalyst
In the haber process, where is the nitrogen from?
The air
In the haber process, where is the hydrogen from?
Hydrocarbons
Explain what is meant by dynamic equilibrium?
When the forward and backward reactions are both happening at the same time and at the same rate
When can equilibrium only be reached?
When a reaction takes place in a closed system
When the equilibrium lies to the right what does this mean?
There are lots of products and not much reactants
When the equilibrium lies to the left what does this mean?
There are lots of reactants but not much of the products
What things affect the position of the equilibrium?
Temperature
Pressure
Concentration
Explain what is meant by a reversible reaction?
A reversible reaction is one where the products can react with each other to produce the reactants
What does Le Chatelier’s principle state?
If theres a change in conc, pressure or temperature in a reversible reaction, the equilibrium position will move to help counteract that change
What happens when you increase the temperature of a reaction?
The equilibrium will move in the endothermic direction to absorb the extra heat
What happens when you decrease the temperature of a reaction?
The equilibrium will move in the exothermic direction to produce more heat
What happens when you increase the pressure of a reaction?
The equilibrium will move to the side with fewer moles of gas to reduce pressure
What happens when you decrease the pressure of the reaction?
The equilibrium will move towards the side that has the most moles of gas to increase pressure
What happens when you increase the concentration of the reactants?
The equilibrium will move to the right to use up the reactants as it makes more products
What happens when you increase the concentration of the products?
The equilibrium will move to the left to use up the products as it makes more reactants
The compound PCl5 can be made using this reaction:
PCl3 + Cl2 ⇌ PCl5
Explain what would happen to the equilibrium position and to the yield of PCl5 if you increased the pressure that the reaction was being performed at
If you increase the pressure the position of the equilibirum will move towards the side with fewer moles of gas to reduce the pressure
As the left has 2 moles and the right has 1 mole, the position of the equilibrium will move to the right since that is the side with fewer moles of gas so the yield of PCl5 will increase
This reaction is endothermic in the forward direction: CH3OH ⇌ CO + 2H2
What will happen to the position of the equilibrium if the temperature is increased?
Explain your answer.
To the right as the forward reaction is endothermic, so when the temperature is increased the equilibrium position will move to the right to absorb the excess heat
What would happen to the yeld of SO3 in the reaction below if the pressure was decreased?
Explain your answer: 2SO2 + O2 ⇌ 2SO3
As the left side has 3 moles and the right has 2, the equilibrium will move to the left as it has the most moles in an attempt to increase pressure, therefore, the yield of SO3 will decrease
Which element is reduced?
CH4 + 2O2 -> CO2 + 2H2O
Oxygen
What is a redox reaction?
A reaction where oxidation and reduction occurs
Describe what happens during a displacement reaction?
The more reactive element displaces the less reactive element
What is a metal ore and where are they usually found?
Rocks with enough metal to make it economically worthwhile to extract and they’re found in the Earth’s crust
Describe how metals less reactive than carbon are usually extracted from their ore?
The ores are heated with carbon, where the carbon displaces the metal
Name two biological methods of extracting methods?
Bioleaching and phytoextraction
Give an advantage and a disadvantage of using bioleaching?
Doesn’t use electricity which is often generated from crude oil, however, it is much slower to extract than electrolysis
If the position of equilibrium lies to the right, what does this tell you about the relative amounts of reactants and products present?
There are more products than reactants
What is a good way of remembering how equilibrium works?
The more reactants/products, the more the ‘seesaw’ is weighed down on that side therefore the equilibrium will move in that direction
Describe what would happen to the equilibrium position if you increased the concentration of the reactants?
The equilibrium moves to the products side as there will be more products made to use up the reactants
