extracting metals and equilibria Flashcards
What does oxidation mean in terms of oxygen?
The addition of oxygen
What is reduction in terms of oxygen?
Removal of oxygen
What do combustion reactions involve ?
Oxidation
Are combustion reactions exothermic or endothermic?
Exothermic
In the reactivity series are they metals or non metals
Metals
What is the order of the reactivity series going down?
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold
Metals at the bottom are more resistant to corrosion, why?
Less resistant to oxidation, corrode easily
The metals at the top of the reactivity series are the most reactive, why?
They easily lose their electrons to form cations
The metals at the bottom of the reactivity series or less reactive, why?
They don’t give up their electrons to form cations as easily
The metals at the bottom of the reactivity series are more resistant to what?
Oxidation
How does magnesium react with dilute hydrochloric acid?
Loud squeaky pop
How does aluminium react to dilute hydrochloric acid?
Fair old squeaky pop
How does zinc react with dilute hydrochloric acid?
Quiet squeaky pop
How does iron react to dilute hydrochloric acid?
Very quiet squeaky pop
How does copper react to dilute hydrochloric acid?
No squeaky pop at all
Very reactive metals like magnesium will do what?
Fizz vigourously
Less reactive metals like zinc will what?
Bubble a bit
Unreactive metals like copper will what?
Not react with dilute acid at all
The faster the bubbles form, the faster the what?
Faster the reaction and more reactive the metal
What does metal and water form?
Metal hydroxide and hydrogen
How do very reactive metals react with water?
Vigourously
How do you less reactive metals react with water?
Steam
Will copper react with water or steam?
No
What are displacement reactions?
Redox reactions
What happens in the displacement reaction?
A more reactive element reacts to take place of a less reactive element in a compound
What happens in metal displacement reactions?
The more reactive metal loses electrons and the less reactive metal gains electrons
What metal is oxidised and what metal is reduced in the displacement reaction?
The more reactive metals is oxidised and the less reactive metal is reduced
If you put a reactive metal into a solution of a reactive metal salt, what will happen?
The reactive metal were replaced the less reactive metal in the salt
What happens if you put a less reactive metal into a solution of a more reactive metal salt?
Nothing will happen
What is a metal ore?
A rock which contains enough metal to make it economically worthwhile extracting metal from it
What is the ore is an ______ of the metal?
Oxide
Where are most of the metals found that we use?
In the ores in the earth crust.
The ores are mined and the metals thing can be extracted from the ores
Some metals can be mined straight out of the ground, but they usually need to be refined before they can be used. What are they called?
Uncombined elements
Some metals can be extracted by reduction with what?
Carbon
When an order is reduced with carbon what is removed?
Oxygen
Metals like magnesium and potassium which are high in carbon have to be extracted using electrolysis metals below carbon like zinc and copper can be reductionist with what?
Using carbon
Why does reduction with carbon only happen with elements lower than carbon?
. This is because carbon can only take the oxygen away from the metals which are less reactive other than carbon itself
How are metal extracted by electrolysis?
Once the metal or is melted, an electric current has passed through the metal is discharged at the cathode and the non-metal at the anode
How is electrolysis so expensive?
Electricity is expensive. There are also cost associated with melting or dissolving the metal or also it can conduct electricity.
What are low-grade ores?
Ores that only contains small amounts of the metal
What are new ways of extracting metals from their ores?
Bioleaching
Phytoextraction
What is bioleaching?
Bacteria is used to separate metals from their ores. The bacteria get energy from the bonds between the atoms in the ore and separate out the metal from the ore in the process. Delete contains metal ions which can be extracted with a more reactive metal.
What is a Leachate?
Solution produced by bioleaching
What is phytoextraction?
Growing plants and soil that contains metal compounds. The plants can’t use or get rid of the metal so they gradually build up in the leaves. the plants can be harvested dried and burnt in furnace as contains metal compounds from which the metal can be extracted by electrolysis or displacement reactions
What does recycling help to do?
Conserve energy and resources
What does recycling do?
It saves energy as this process often only uses a small fraction of the energy needed to extract and refined the material from scratch
What materials are important to recycle?
Rare materials
How does extracting metals impact the environment?
Damages the environment and destroys habitats
What are some economic benefits of recycling?
It saves money
Beneficial to the economy to recycle materials that are expensive to extract or buy
Create a lot of jobs
What do you life cycle assessment show?
Environmental costs
What does life cycle assessment do?
Looks at each stage of the life of a product from making the material from raw natural materials to making the product, from the materials, using the product and disposing of the product. It works out each potential environmental impact of each stage.
What happens in life-cycle assessment in the choice of material stage?
Metals have to be mined and extracted from their ores. These processes need a lot of energy and cause a lot of pollution.
Raw materials for chemical manufacture often come from crude oil crude oil is a nonrenewable source and supplies are decreasing also obtaining crude oil from the ground and refining it into useful raw materials requires a lot of energy and generates pollution
What happens in a life cycle assessment of the manufacture stage?
Manufacturing product uses a lot of energy and other resources
It can also cause a lot of pollution
You need to think about any product and how to dispose of them . Some waste can be recycled and turned into other useful chemicals reducing the amount that ends up polluting the environment.
Chemical manufacturer needs water businesses have to make sure they don’t put polluted water back into the environment at the end of the process
What happens in the life-cycle assessment in the product use stage?
Using the product can also damage the environment for example paint gives off toxic fumes, burning fuels release greenhouse gases and other harmful substances, fertilisers can leach into seams and rivers and cause damage to ecosystems
What happens in the life cycle assessment of the disposal stage?
Products are often disposed of in a landfill site at the end of their life, this takes up space and pollute land and water
Products might be burned which causes air pollution
What is the Haber process and example of?
Reversible reactions
What is the haber process?
Nitrogen and hydrogen react to form ammonia
The haber process is carried out at 450°C with a pressure of 200 atmospheres and an iron catalyst
Where can nitrogen be obtained?
From the air, which is about 78% nitrogen
Where can hydrogen be extracted from?
Hydrocarbons from sources such as natural gas and crude oil
What is a reversible reaction?
Where the products can react with each other to produce the original reactants. It can go both ways.
Reversible reactions will reach what?
Equilibrium
What is equilibrium?
As the reactants react, their concentrations fall - so the forward reaction will slow down. But as more and more of the products are made and their concentrations rise, the backward reaction will speed up.
After a while, the forward reaction will be going exactly at the same rate as the backward one - this is equilibrium.
At equilibrium both reactions are still happening, but there’s no overall effect.
What is a dynamic equilibrium?
The forward and back reactions are both happening at the same time and at the same rate, and the concentrations of reactants and product have reached a balance and won’t change.
Can equilibrium be reached in a open system?
No, it can only happen in a closed system
What is a closed system?
None of the reactants or products can escape
Sometimes equilibrium will lie to the right what does this mean?
There is a higher concentration of products than concentration of reactants
Sometimes the equilibrium will lie to the left. What does this mean?
The concentration of reactants is higher than the concentration of products
What are three things that change the position of equilibrium?
Temperature
Pressure
Concentration
What does Le Chatelier principle state?
If there is a change in concentration, pressure or temperature in a reversible reaction, the equilibrium position will move to help counteract that change
Explain a change in temperature according to Le Chatelier’s principle and equilibrium
If you decrease the temperature, the equilibrium will move in the exothermic direction to produce more heat
If you increase the temperature, the equilibrium will move in the endothermic direction to absorb the extra heat
Explain a change in pressure according to Le Chatelier’s principle and equilibrium
(Only involves gases)
If you increase the pressure, the equilibrium will move towards the side that has fewer molecules of gas to reduce pressure
If you decrease the pressure, the equilibrium will move towards the side that has more molecules of gas to increase pressure
Explain a change in concentration according to Le Chatelier’s principle and equilibrium
If you increase the concentration of the reactants, the equilibrium will move to the right to use up the reactants (making more product)
If you increase the concentration of the product , the equilibrium will move to the left to use up the product (making more reactants)
Decreasing the concentration will have the opposite effect
The compound PCl5 can be made using this reaction: PCl3 + Cl2 (reverse) - PCl5. explain what would happen to the equilibrium position and the yield of PCl5 if you increase the pressure that the reaction was being performed at.
According to Le Chatelier’s principle, if you increase the pressure, the position of equilibrium will move towards the side with fewer molecules of gas to reduce the pressure. In this reaction there are two molecules of gas in the reactants and one in the products. The position of equilibrium will move to the right since that is the side of the fewer molecules of gas. This shift the equilibrium towards the products, so the yield of PCl5 will increase.
