C5 Separate Chemistry 1 Flashcards
What are properties of transition metals?
- High melting point
- High density
- Catalyst
- Form colourful compounds
Why do we use alloys instead of pure metals?
Alloys have different size atoms with upset the layers of the pure metal atoms, making it more difficult for them to slide over each other and so stronger
What are the different methods to prevent rusting?
- Painting
- Oiling or greasing for moving parts
- Sacrificial protection - placing a more reactive metal in front of the metal
Why is electroplating used?
- It can make metals unreactive
- It can improve appearances of metals
Why is a pressure of 200atm used in the Haber process?
It is as high as possible to give the best yield without making the plant expensive or dangerous
Why is a temperature of 450C used in the Haber process?
It gives a high reaction rate even though it moves the equilibrium the wrong way
What effect do catalysts and conditions have on the time taken to reach equilibrium?
If increased, they reduce the time taken to reach equilibrium
Why are NPK fertilisers soluble?
So they can dissolve down into the soil and be absorbed by plants
How does hydrogen-oxygen fuel cells produce electricity?
Hydrogen and Oxygen react together, producing water and a voltage
What are the advantages of hydrogen-oxygen fuel cells?
- They produce no greenhouse gases
- There are no moving parts so energy isn’t lost due to friction
What are the disadvantages of hydrogen-oxygen fuel cells?
- Hydrogen is a gas so it takes up lots of space to store
- It’s very explosive so it’s difficult to store safely
