C1 Part A Flashcards
Give the symbol equation for the thermal decomposition of limestone:
CaCO3→ CaO + CO2
Which other substances thermally decompose in the same way as limestone?
Magnesium, copper, zinc and sodium carbonate
Give the word and symbol equation for the reaction that causes limestone to be damaged by acid rain.
Calcium Carbonate + Sulfuric acid → Calcium sulfate + Carbon dioxide + Water
CaCO3 + SO4→ CaSO4 + CO2+ H2O
What product is formed when you react calcium carbonate with water?
Calcium Hydroxide
Calcium hydroxide is an alkali which means it can be used to neutralise……. and does this much faster than …………
It is also used to indicate the presence of ……….. when ……… . It becomes ……….. if there’s …….. and this is due to the formation of …………
- Used to neutralise acidic soil in fields and does this much faster than powdered limestone
- Indicates the presence of Carbon Dioxide when gas is bubbled through it. It becomes cloudy if there’s Carbon Dioxide in the gas - this is due to the formation of Calcium Carbonate.
How is powdered clay used to make cement and what happens when cement is mixed with sand and water?
It is heated in a kiln with clay. When cement is mixed with sand and water it becomes mortar.
What happens when clay is mixed with sand and aggregate?
Concrete is made
List the issues with quarrying limestone (5)
- Huge holes change the landscape permanently (however restoration of the area is usually required after quarrying work has been finished)
- Quarrying processes (eg. blasting rocks apart with explosives) make a huge amount of noise
- Quarrying destroys habitata
- Limestone must be transported elsewhere to be made into other products, creating more noise and pollution.
- Waste materials produce unsightly tips
How do cement factories harm people and the environment? (2)
- They create a lot of dust, which can cause breathing problems.
- A huge amount of energy is needed, most of this will come from burning fossil fuels (which pollutes the atmosphere).
What are the informal names for Calcium Oxide and Calcium Hydroxide?
Calcium Oxide: Quicklime
Calcium Hydroxide: Slaked lime
What are some of the uses of Limestone products? (5)
- Concrete and cement are building materials
- Chemicals can be used in dyes, paints and medicine
- Used to neutralise acidic soil, lakes and rivers
- In power station chimneys to neutralise sulfur dioxide (a cause of acid rain)
Why is limestone so widely used? (4)
- It is cheaper than granite or marble
- Fairly easy to cut
- More hardwearing than marble
- Limestone, concrete and cement don’t rot like wood does when it gets wet and they’re fire-resistant.
List some advantages (3) and disadvantages (3) of concrete
Advantages
- Can be poured into moulds
- It’s cheap
- Concrete doesn’t corrode and it’s fire resistant
Disadvantages
- Emissions from the concrete and cement industry contribute to the greenhouse gas effect (and climate change)
- Concrete has a low tensile strength and can crack, meaning often it must be reinforced with steel bars
- It’s deemed to be ugly as a building material
What is a metal ore?
A rock that contains enough metal for it to be worthwhile extracting
What is the main aluminium ore, name and symbol?
Bauxite, aluminium oxide
Al2O3
Which two economic factors contribute to how worthwhile extracting a metal is?
- The market price of the metal (if it drops, it might not be worth extracting)
- Improvements in technology mean that extraction that might not have been worthwhile in the past, now is
By which two methods can metals be extracted from their ores?
Chemically (by reduction)
By Electrolysis
Some metals can be extracted from their ores by reduction with ……………. When an ore is reduced, this means ………… has been removed from it.
Some metals can be extracted from their ores by reduction with carbon. When an ore is reduced, this means oxygen has been removed from it.
Which metals can be extracted using reduction? (4)
Those lower in the reactivity series than carbon:
Zinc, Iron, Tin, Copper
Give the symbol and word equation for the reduction process used to extract iron.
Where does this occur in industry?
2Fe2O3 + 3C → 4Fe + 3CO2
Iron (III) Oxide + Carbon → Iron + Carbon Dioxide
In a blast furnace
Which metals are extracted by electrolysis? (5)
Those higher in the reactivity series than carbon:
Potassium, Sodium, Calcium, Magnesium, Aluminium
Why is electrolysis much more expensive than reduction?
It requires a lot of energy, both to melt the ores and charge the elctrodes.
How else is electrolysis used, other than for extraction? Give an example that includes a specific metal
Purification of metals
Copper produced by reduction is impure. Electrolysis is used to form a very pure copper, which is much better at conducting.
What is an electrolyte and how do they conduct electricity?
A liquid used to conduct in the process of electrolysis, often metal salt solutions made from the ore of the metal being extracted or molten metal oxides.
Electrolytes have free ions that enable electricity to be conducted.
Explain the process of electrolysis specific to copper, draw a diagram if it helps (3 main steps)
Anode - positive electrode
Cathode - negative electrode
- Electrons are taken from copper atoms at the anode, causing them to enter the copper sulfate solution (electrolyte) as Cu2+ ions.
- Cu2+ ions near the cathode gain electrons and become copper atoms
- Impurities are left at the anode as a sludge, pure copper atoms bond to the cathode.
In copper electrolysis, what are the cathode and anode made of?
Cathode - Begins as a thin strip of pure copper that grows as electrolysis occurs
Anode - a lump of impure copper that will dissolve
Why are alloys harder than pure metals?
Different elements consistent of different sized atoms. When they are added to one another, the element with the smaller atoms will upset the layers of the element with larger atoms, making them more difficult to slide over one another.
