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GCSE Chemistry > Extracting Metals And Equilibra > Flashcards

Extracting Metals And Equilibra Flashcards

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1
Q

What are the products when a metal reacts with cold water?

A

Metal hydroxide and hydrogen gas

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2
Q

What are products when a metal reacts with steam?

A

Metal oxide and hydrogen gas

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3
Q

Write the chemical equation for the reaction that occurs when calcium reacts with cold water

A

Ca + 2H2O —> Ca(OH)2 + H2

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4
Q

Write the chemical equation for the reaction that occurs when zinc reacts with steam

A

Zn + H20 —> ZnO + H2

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5
Q

What are the products when a metal reads with a dilute acid?

A

Salt and hydrogen

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6
Q

If a metal reacts with cold water, what does it suggest about the reactivity of this metals?

A

It suggest that metal is very reactive as only the most reactive metals can react with cold water.

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7
Q

A metal reacts with oxygen but not acid or cold water. What does this suggest about the reactivity of this metal?

A

Not very reactive, most metals react with oxygen.

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8
Q

Name a metal which will not react with water, acid or oxygen

A

Gold

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9
Q

Describe an experiment that uses displacement to compare the reactivity of two metals

A

Add a solid metal to a salt solution (the Salt must contain a different metal)

If the solid metal is more reactive, it will gradually disappear, displacing the metal that was in the salt solution.

If nothing happens, the metal in the salt is more reactive and can’t be displaced.

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10
Q

What would you expect to observe when magnesium is added to copper sulfate solution?

A

Copper sulfate is blue. Magnesium is more reactive than copper so when magnesium is added the blue solution decolourises and copper coats the surface of the magnesium.

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11
Q

Why can a displacement reaction be called a redox reaction. Explain in terms of electron transfer

A

A redox reaction occurs when reduction and oxidation are taking place in the same reaction.

In a displacement reaction, the more reactive metal atoms loses electrons to form ions (oxidation) and the less reactive metals ions gains electrons to form the element (reduction)

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12
Q

What is the reactivity of a metal?

A

It is the tendency of the a metal to form cations (positive ions)

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13
Q

Why can displacement reaction be called a redox reaction. Explain in terms of electron transfer

A

A redox reaction occurs when reduction and oxidation are taking place in same reaction.

In a displacement reaction, the more reactive metal atoms lose electrons to form ions (oxidation) and the less reactive metal ions gain electrons to form the element (reduction).

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14
Q

What is the reactivity of a metal?

A

It is the tendency of a metal to form cations

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15
Q

Which metals are most easily oxidised?

A

The metals highest in the reactivity series. More reactive metals are more likely to react with water and dilute acids to form cations.

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16
Q

Where are most metals extracted from?

A

From ores found in the Earth’s crust

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17
Q

What is an ore?

A

A rock which contains metals often chemically combined with other substances.

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18
Q

Which metals are found in the earths crust as uncombined elements?

A

Gold,silver, platinum - unreactive metals

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19
Q

Explain what oxidation means in terms of oxygen

A

Gain of oxygen

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20
Q

Explain what reduction means in terms of oxygen.

A

Loss of oxygen

21
Q

Most ores contain metals chemically combined with oxygen. What process must be carried out to extract the metal?

A

Reduction

22
Q

Which two methods could be used to extract metals from their ores?

A

Reduction with carbon: can only be done if the metal is less reactive than carbon (links to reactivity series)

Electrolysis: can be done with all metals, but requires a large amount of energy (high cost)

23
Q

How would you extract iron from its ore?

A

Iron is less reactive than carbon so can be extracted by reduction with carbon.
Electrolysis could be used, but this would use a lot unnecessary energy (high cost).

24
Q

What’s the chemical equation for reduction of iron with carbon?

A
25
Q

How can aluminium be extracted from its ore?

A

Aluminium is more reactive than carbon so electrolysis must be used.

When molten ore undergoes electrolysis the metal forms at the cathode.

26
Q

When aluminium is extracted from aluminium oxide, why is it first dissolved in molten cryolite?

A

Aluminium oxide has a very high melting point. It is dissolved in molten cryolite to produce an electrolyte with a lower melting point, reducing energy usage and cost.

27
Q

How can plants be used as an alternative extraction method? How does it work?

A

Phytoextraction:
Plants are grown in areas with metals in the soil. The plants take up metals through their roots and concentrate them in their shoots and leaves. These plants are burned and the metals extracted from the ash.

28
Q

How can bacteria be used as an alternative metal extraction method? How does it work?

A

Bacterial extraction:
Some bacteria absorb metal compounds. These bacteria produce solutions called leachates containing the metals. Scrap iron can be used to remove the metal from the leachate.

29
Q

What are limitations of biological methods of extraction?

A

Only suitable for low grade ores with smaller quantities of metals.
Slow processes
Requires displacement or electrolysis for the final step.

30
Q

How is a metal’s relative resistance to oxidation related to its position in the reactivity series?

A

Oxidation is the loss of electrons. Metals lower in the reactivity series are less reactive. This means they are less likely to form their cations so are more resistant to oxidation.

31
Q

What are advantages of recycling metals?

A

Economically beneficial because electrolysis is expensive
Prevents the detrimental environment impact of mining and extraction of new metals.
Less energy required compared to electrolysis
More sustainable- not using finite resources
Recycling process provides employment.

32
Q

What is a life cycle assessment?

A

Analysis of the overall environmental impact that a product may have throughout its lifetime.

33
Q

What difference factors does a life cycle assessment of a product consider?

A 
Extraction and processing of raw materials 
Manufacturing 
Packaging and transportation 
Use of the product 
Disposal
34
Q

What is reversible reaction?

A

A reaction in which the products can reaction to form the original reactants

35
Q

How can direction of a reversible reaction be altered?

A

Changing reaction conditions

Temperature, pressure, concentration

36
Q

What is meant by dynamic equilibrium?

A

Dynamic equilibrium is when the rate of the forward reaction equals the rate of the backwards reaction. This means the concentration of reactants and products are constants even though compounds are continually reacting.

37
Q

What is a closed system?

A

A system where nothing is added or removed. All reactants and products remain in the reaction vessel.

38
Q

Why is equilibrium only reached if the reaction takes place in a closed system?

A

The closed system prevents any reactants and products escaping so that they are able to react continuously.

39
Q

What haber process?

A

Industrial process for making ammonia(used in fertilisers)

40
Q

Write the chemical equation for reversible between nitrogen and hydrogen, forming ammonia?

A
41
Q

Where the sources of nitrogen and hydrogen for the haber process?

A

Nitrogen: extracted from the air
Hydrogen: obtained from natural gas

42
Q

What conditions are used for the haber process?

A

450°C
200 atm pressure
Iron catalyst

43
Q

Explain the effect of changing the temperature of a reversible reaction if the forward reaction is endothermic

A

The forward reaction is endothermic so increasing temperature favours the forward reaction (system tries to reverse the change). The equilibrium will shift towards the forward reaction and the yield of the products will increase.

44
Q

Explain the effect of changing the pressure of a reversible gaseous reaction.

A

An increase in pressure will favour the reaction that produces the least number of molecules. The equilibrium position will shift towards the side that produces the fewest gaseous molecules.

45
Q
A

Increasing the pressure will shift equilibrium to the right as there are fewer molecules of gas. The yield of ammonia will increase.

46
Q

The concentration of the reactants are increased during a reversible reaction. What effect will this have on equilibrium position?

A

The equilibrium will shift to the right so that product yield will increase. This will reduce the effect of increased concentration of the reactants.

47
Q

If there are equal gaseous molecules on either side of a reaction, what effect will changing the pressure have on the equilibrium position?

A

No effect.

48
Q

Recall the reactivity series: and what reacts with water(cold) and dilute acid.

A

GCSE Chemistry (13 decks)

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