Separate Chemistry 1 Flashcards

1
Q

What are the typical properties of transition metals?

A
  • High melting point (except mercury)
  • High density
  • Stronger and harder than the metals in group 1 and 2 (often used for construction )
  • Formation of coloured compounds
  • Catalytic activity
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2
Q

What is a catalyst?

A
  • Increase the rate of a chemical reaction
  • Without altering the products of the reaction
  • Without changing chemically
  • Without changing in mass at the end of the reaction
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3
Q

What are the properties of group 1 and 2 elements?

A
  • Relatively low melting point
  • Relatively low density
  • Formation of white or colourless compounds
  • Lack of catalytic activity
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4
Q

What are the reasons for not obtaining the theoretical yield?

A
  • Incomplete reactions – reaction hasn’t finished, reaction reaches equilibrium
  • Side reactions – competing, unwanted reaction is so bi-products are also made
  • Practical losses – losses during purification (e.g. filtration), losses during transfers (e.g. liquid left behind in containers)
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5
Q

What is atom economy?

A

A way of measuring the number of atoms wasted when making a substance

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6
Q

How can rusting be prevented using physical barriers?

A
  • Painting
  • Using oil or grease
  • Coating with plastic
  • Coating with another metal
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7
Q

How would you carry out a rusting experiment?

A
  • Place a nail in a test tube with air and water
  • Place a nail in a test tube filled with water with a layer of oil on top
  • Place a nail in a test tube with calcium chloride (which absorbs water)
  • Only the nail with water and air will rust
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8
Q

How does electroplating work?

A
  • Electrolysis is used to put a thin layer of metal on the object
  • The cathode is the iron or steel object
  • The anode is the plating metal
  • The electrolyte contains ions of the plating metal
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9
Q

What is it sacrificial protection?

A

If iron is in contact with a more reactive metal (zinc), the more reactive metal oxidises more readily than the iron so it ‘sacrifices’ itself

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10
Q

How does galvanising prevent iron from rusting?

A
  • The zinc layer stops oxygen in water reaching the iron
  • The zinc is more reactive than iron so it also acts as a sacrificial metal
  • This means the protection works even if the zinc layer is scratched
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11
Q

Why are alloys often stronger than pure metals?

A
  • Pure metals have a regular lattice structure with layers that slide over each other
  • Alloys have different sized ions that disrupt the regular structure and prevent it from sliding easily
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12
Q

What are some examples of alloy steels?

A

Mild steel (carbon) – malleable, ductile

Tool steel (tungsten) – hard, resistant to high temperatures

Stainless steel (chromium) – hard, resistant to rusting

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13
Q

What are the properties of aluminium?

A
  • Low density, used for aircraft
  • Does not react with water, used as foil for storing food
  • Malleable, **
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14
Q

What are the properties of copper?

A
  • Resists corrosion
  • Good electrical conductors, used in wires
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15
Q

What are the properties of gold?

A
  • Resists corrosion and stays shiny, used for jewellery
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16
Q

What are the properties of magnalium (aluminium + magnesium) ?

A
  • Low-density and stronger than aluminium, used in cars and planes
17
Q

What are the properties of brass (copper + zinc) ?

A
  • Hard, resistant to corrosion, still conducts electricity, used for the pins in electrical plugs
18
Q

What is the equation for concentration?

A

Concentration (mol dm^-3) =

Amount of solute (mol)
/
Volume of solution (dm^3)

19
Q

How do you calculate the percentage yield?

A

Actual yield / Theoretical yield
x
100

20
Q

How do you calculate atom economy?

A

Total Mr of desired products /
Total Mr of all products
x
100

21
Q

When is the atom economy 100%?

A
  • If there is only one product
  • All of the byproducts are used
22
Q

What should you look for when explaining why particular reaction pathway is chosen?

A
  • High atom economy
  • High yield
  • Fast rate
  • Equilibrium position to the right
  • Useful byproducts
23
Q

What is Avogadro’s law?

A

Equal volumes of different gases contain an equal number of molecules

When temperature and pressure stay the same

24
Q

What is molar volume?

A

The volume occupied by one mole of molecules of any gas at room temperature and pressure

25
Q

How do you calculate the volume of gas? (molar volume)

A

Molar volume x amount

26
Q

How do you calculate the amount of gas? (molar volume)

A

Volume of gas / Molar volume

27
Q

Why is the temperature compromised in the Harber process?

A
  • High temperature shift equilibrium towards the reactants
  • But if it is not high enough the rate of reaction will be slow
28
Q

What NPK fertilisers?

A

Fertilisers that contain:

  • Nitrogen
  • Phosphorus
  • Potassium
29
Q

How does ammonia react with nitric acid to produce a fertiliser salt?

A

- Ammonia acts as a base

  • Ammonia + Nitric acid > Ammonia nitrate
30
Q

How is ammonium sulphate made in a lab?

A
  • By reacting ammonia solution and dilute sulfuric acid 
  • Brought from chemical manufacturers
  • Only involves titration and crystallisation
  • Small scale production
31
Q

How is ammonium sulphate made in industry?

A
  • By reacting natural gas, air, water (ammonia)
  • And sulfur, air, water (sulphuric acid)
  • Many stages: needs to make ammonia, sulphuric acid, react accurate volumes, evaporate
  • Large-scale production
32
Q

What is a hydrogen-oxygen fuel cell?

A
  • Hydrogen and oxygen are used to produce a voltage
  • Water is the only product
33
Q

What are the advantages of fuel cells?

A
  • Produce only water as waste, no pollution
  • Keep producing a voltage as long as fuel and air are supplied
34
Q

What are the disadvantages of fuel cells?

A
  • Not suitable for portable devices as they are difficult to transport
  • Expensive to make