4) Extracting Metals & Equilibria Flashcards
What is the oxidation and reduction acronym?
OIL RIG
What does an oxidation reaction involve?
Gaining oxyxgen
Losing electrons
What happens when a metal reacts with oxygen?
Metal oxides are produced
Magnesium + oxygen –> magnesium oxide
What does a reduction reaction involve?
Losing oxygen
Gaining electrongs
What happens when metal oxides lose oxygen?
They return to their atomic form
Iron oxide + carbon monoxide –> iron + carbon dioxide
What type of ion do metal atoms always form?
Positive cations
What do we call very unreactive metals such as gold and platinum?
Native metals
What is the reactivity of a metal linked to?
How easy it is to form its positive ion
What happens in a displacement reaction?
A more reactive metal displaces a less reactive metal from a compound
What is an example of a redox reaction?
Displacement
WHat happens in metal displacement reactions?
More reactive metal is oxidised
Less reactive metal is reduced
What do we call ions that do not change in reactions?
Spectator ions
What type of reaction has added electrons in the products?
Reduction
What type of reaction has added electrons in the reactants?
Oxidation
What happens when the alkali metals react with water?
A metal hydroxide and hydrogen gas is produced
What happens when potassium reacts with water?
Ignites instantly
Sparking and burning with lilac flame
What happens when sodium reacts with water?
Fizzes rapidly and melts to form a ball that moves on water’s surface
What happens when lithium reacts with water?
Fizzes steadily and floats, becoming smaller until it disappears
How does reactivity change for the alkali metals?
Reactivity increases up the group
What metals don’t react with dilute acids?
Copper
Silver
Gold
Platinum
What does most metals react with dilute acids to form?
Salt
Hydrogen gas
Why is carbon used to extarct metals?
High on reactivity series
Cheap and abundant
How is carbon used to extract metals?
In the reduction, metal oxide loses oxygen to form a pure metal
Usually metal oxide is heated in presence of carbon uusally in coal form
What 5 metals react with dilute acids but not water?
Magnesium Aluminium Zinc Iron Lead
What is phytomining?
Extracting copper from contaminated land
What is the process of phytomining?
1) Plants growing on contaminated land absorb copper ions
2) These plants are harvetsed and burned producing ash containing high concentrations of copper compounds
What is a disadvantage of phytomining?
Takes longer than other methods
What is the process of bioleaching?
1) Bacteria are added to low-grade ores
2) Bacteria breaks down ores creatinga solution rich in copper compounds (leachate solution), we can easily extract copper from leachate solution
WHat is a disadvantage of bioleaching?
Slower than traditional mining
What does the process of recycling metals involve?
Melting metals before reshaping them
Why is recycling metals preferable to mining and extracting new resources?
Less energy required
Reduced burning of fossil fuels
Conserves finite resources
Fewer waste rock heaps
What do LCAs assess?
All 4 stages of a product’s life cycle to calcualte its environmental costs
What does LCA stand for?
Life Cycle Assessment
What are thhe 4 stages of a product’s lifecycle?
1) Collecting raw materials needed
2) Making and packaging product
3) Product use
4) Disposal of product
What are reversible reactions?
When the reactants and products can combine each way
What is endo and exothermic reaction’s relation to reversible reactions?
If the forward reaction is exothermic, the backwards reaction will be endothermic
How much energy is relseased compared to energy absorbed in reversible reactions?
Energy relseased is exaclty equal to energy absorbed
What is an example of a reversible reaction?
The Haber process
What is formed in the Haber process?
Ammonia through the reaction of nitrogen and hydrogen
What temperature and pressure if the Haber process carried out at?
450 degrees C with a pressure of 200 atmospheres
When does a dynamic equilibrium occur?
When reversible reactions happen within a closed system
What is a closed system?
A system where reactants and products can not be added or removed
How does reaction rate and concentration of products and reactants change in a dynamic equilibrium?
Equal reaction rate
Concentrations of reactants and products do not change
What do the conditions of a reversible reaction deermine?
The relative quantities of the different reactants and products in a reaction at equilibrium
What does Le Chatelier’s principle state?
If any of the conditions of a reversible reaction at equilibrium change, the closed system will counteract whatever has changed
What is Le Chatelier’s principle used to predict?
The outcome of any changes imposed on a system at equilibrium
What does a decrease in temperature cause in equilibrium?
The position of equilibrium will shift in the exothermic direction
How does a decrease in temperature affect the amount of products and reactants generated?
Products generated by exothermic reaction increases
Products generated by endothermic reaction decreases
What does an increase in temperature cause in equilibrium?
The position of equilibrium will shift in the endothermic direction
How does an increase in temperature affect the amount of products and reactants generated?
Products generated by endothermic reaction increases
Products generated by exothermic reaction decreases
How does an increase in pressure affect the position of equilibrium?
Position shifts to favour reaction producing fewest gas molecules
How does a decrease in pressure affect the position of equilibrium?
Position shifts to favour reaction producing most gas molecules
What must be assessed to predict the outcome of a pressure change?
Balanced equations to see how many gas molecules are one ach side of the equation
How does an increase in concentration of a reactant in equilibrium shift the position?
Forward reaction is favoured
Equilibrium position shifts towards products
How does an increase in concentration of a product in equilibrium shift the position?
Backwards reaction is favoured
Equilibrium position shifts towards reactants
