C2 - Chemical Resources Flashcards
(27 cards)
How is cement made?
By heating powdered limestone with clay
How is concrete made?
By mixing cement, aggregate, sand and water
Explain how copper is extracted from copper ores. Give a word and balanced symbol equation
Copper ores are crushed and heated with carbon. This works because carbon is more reactive than copper.
Crushed copper ore is heated (thermal decomposition):
- CuCO3 -> CuO + CO2
The copper oxide produced is heated with carbon:
- 2CuO + C + 2Cu + CO2
Explain how copper is purified in electrolysis
Refer to diagram in notebook
State 2 benefits and 1 drawback of recycling copper
Benefits:
- It is cheaper to recycle copper than to extract it from ores
- Recycling copper makes good use of a valuable limited resource
Drawbacks:
- Once thrown away, copper can be difficult, time-consuming and expensive to recycle as it has to be hand-sorted prior to this
Define ‘alloy’
A mixture of 2 or more elements, at least one of which is a metal
State the main metals in amalgam, brass and solder, and state a use for each alloy
- Amalgam - mercury - tooth fillings
- Brass - copper and zinc - coins, musical instruments
- Solder - lead and tin - joining electrical wires
State an example of a ‘smart’ alloy, the name of the alloy, and its uses regarding how it works
- Shape-memory alloys
- Nitinol
- Used for spectacle frames - returns to its original shape at room temperature, if spectacle frames are bent out of shape
State 2 similarities and 3 differences between iron and aluminium
Similarities:
- Both malleable (bent into shape easily)
- Both good electrical conductors
Differences:
- Iron corrodes easily, aluminium doesn’t
- Iron is magnetic, aluminium isn’t
- Aluminium is more dense that iron
Discuss the advantages and disadvantages of building car bodies from steel or aluminium
- Steel is cheaper
- Steel corrodes in moist conditions unless protected by a layer of paint
- Aluminium is less dense, so it will provide a better fuel economy as the car will weigh less
State 2 benefits of recycling cars
- It saves natural resources
- It solves the problem of how to dispose of cars once used
State the 5 factors that affect the cost of making new substances
- Cost of factory equipment
- Energy costs
- Labour costs
- Speed at which new substance is made
- Cost of starting materials
State 2 uses of ammonia
- Making fertilisers which replace the essential elements in soil needed by plants to grow, increasing crop yields which can benefit food production
- Cleaning fluids - because it reacts with grease
Explain the justifications for the conditions used in the Haber process
- Pressure of 200 atmospheres - the higher the pressure, the higher the yield, however, a high pressure requires stronger and more expensive factory equipment so a compromise pressure of 200 atmospheres is chosen
- Temperature of 450’C - increasing temperature increases rate of reaction but decreases yield, so a compromise temperature of 450’C is used to give a good yield and a good rate of reaction
- Iron catalyst - used to increase the rate of reaction and remains unchanged at the end of the reaction
How are costs reduced in the Haber process (2 ways)
- Unreacted hydrogen and nitrogen are recycled so that all of the products are used
- Iron catalyst is reused for many reactions as it remains unchanged at the end of the reaction
What are the 3 essential elements needed by plants?
- Nitrogen
- Potassium
- Phosphorus
Explain simply how fertilisers increase crop yields
They provide plants with more of the essential elements they need to grow (by replacing lost elements in soil)
Name 2 nitrogenous fertilisers made from ammonia
- Ammonium sulfate
- Ammonium nitrate
- Ammonium phosphate
Describe how to make a fertiliser compound in the lab
- Measure a known volume (usually 25cm3) of alkali using a measuring cylinder and transfer this to a conical flask
- Add a few drops of phenolphthalein to the solution
- Add acid from the burette to the solution until the colour of the solution just changes
- Note the volume of acid added
- Repeat steps 1-4 without adding phenolphthalein
- Heat the solution to reduce its volume and leave it to cool to allow crystals to form
- Filter the crystals from the solution using filter paper and a filter funnel
- Leave the crystals to dry
State 3 ways of obtaining sodium chloride
- Heating sea water to evaporate it
- Mining salt deposits by cutting
- Solution mining (salt deposits)
What is another name for sodium chloride solution?
Brine
State the name of and explain, the problem which may be caused by mining salt
Subsidence - where the land slumps down due to a mine below, damaging land and buildings
State the 3 products formed by the electrolysis of brine and state a use of each
- Hydrogen - used in the manufacture of margarine
- Chlorine - used to sterilise drinking and swimming pool water
- Sodium hydroxide - used to make bleach (sodium chlorate) by reacting with chlorine
State the word equation for making bleach
sodium hydroxide + chlorine -> sodium chloride + water + sodium chlorate (bleach)
