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GCSE Chemistry > Topic 4 - Chemical Changes > Flashcards

Topic 4 - Chemical Changes Flashcards

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1
Q

Describe how metals react with oxygen

What types of reactions are they and why?

A

Metals react with oxygen to produce metal oxides.

The reactions are oxidation reactions because the metals gain
oxygen.

When metals react with oxygen to form metal oxides and an oxidation reaction takes place

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2
Q

what is an ore

A

A compound from which a metal can be extracted for profit

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3
Q

iron + oxygen —->

A

iron + oxygen —> iron oxide

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4
Q

iron + oxygen —> iron oxide
in this reaction which element has been oxidised

what type of reaction is this

A

The iron has been oxidised because the iron has gained oxygen

This is an oxidation reaction because iron is gaining oxygen.

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5
Q

metal + oxygen —> metal oxide
in this reaction which element has been oxidised

A

the metal atoms have been oxidised

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6
Q

What is an oxidation reaction

A

Gaining oxygen is called a oxidation reaction

A reaction where oxygen is added to a substance or when electrons are lost from a substance

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7
Q

What is a reduction reaction

A

A reaction where oxygen is removed from a substance or electrons are gained

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8
Q

magnensium oxide —> magneisum + oxygen

what type of reaction is this and why?
what has happened

A

This is a reduction reaction become oxygen is being lost (removed) from the substance (magnesium oxide)

Here the magnesium atoms have been reduced

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9
Q

calcium + copper oxide –> calcium oxide + copper

which element has been oxidised and which element has been reduced

A

The calcium has been oxidised because it has gained oxygen (it has gone from calcium to calcium oxide)

The copper has been reduced because it has lost oxygen (it has gone from copper oxide to oxide)

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10
Q

metal + water–>

A

metal + water —> metal hydroxide + hydrogen

metal hydroxides are alkali’s

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11
Q

State the reactivity series

A

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
(Carbon)
Zinc
Iron
Tin
Lead
(Hydrogen)
Copper
Silver
Gold
Platinum

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12
Q

What happens when metals react

A

When metals react, they lose electrons and form positive ions

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13
Q

show potassium forming the potassium ion

A

K —> K+ + e-

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14
Q

What does the reactivity of a metal depend on

What is the reactivity series based on

A

The reactivity of a metal depends on its tendency (ability/how easily they) to lose electrons and form a positive ion.

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15
Q

K —> K+ + e-

A

It shows potassium forming the potassium ion, K+ and losing one electron

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16
Q

In terms of a metals tendency to form a positive ion, what does it show to us regarding the reactivity series

A

More reactive metals readily ( will more easily/have a higher tendency) to lose electrons and form a positive ion while less reactive metals are much less likely (will less easily/lower tendency) to form a positive ion

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17
Q

potassium reaction with water

A

produces the alkali, potassium hydroxide and the gas, hydrogen

extremely vigorous reaction (lilac flame can be seen)

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18
Q

sodium reaction with water

A

produces the alkali, sodium hydroxide and the gas, hydrogen

reacts less rapidly with water than potassium

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19
Q

lithium reaction with water

A

produces the alkali, lithium hydroxide and the gas, hydrogen

reacts more slowly than potassium or sodium

20
Q

reaction with water for potassium, sodium, lithium, (at room temperature) calcium

A

fizz, giving off hydrogen gas, leaving an alkaline solution of metal hydroxide

reacts very rapidly with water at room temp.

calcium - reacts quite rapidly with water at room temp.

21
Q

reaction with water for magnesium, aluminium, zinc, iron

A

very slow reaction

(or no reaction with water at room temp.)

22
Q

reaction with water for tin and lead

A

slight reaction with steam

23
Q

reaction with water for copper, silver and gold

A

no reaction, even with steam

24
Q

How to work out reactivity of metals

A

By testing a range of different metals with water, we can work out the reactivity of the metals

25
Q

Using the metals reactivity with water, which metals can you determine their reactivity.

Why is this only a few?

A

The metal’s reaction with water can be used to determine the reactivity of potassium, sodium, lithium and calcium.
We cannot use water to determine the reactivity of mg,zn,Fe and Cu as they do not react with water

26
Q

How to compare the reactivity of mg, zn, Fe, cu

A

To compare the reactivity of these metals, then react them with dilute acid

27
Q

reaction with dilute acid for K, Na, Li, Ca

A

Explode
Dangerously fast reaction with acids

Calcium - Extremely vigorous reaction

28
Q

reaction with dilute acid for mg, al, zn, Fe

A

Fizz giving off hydrogen gas and forming a salt

mg - rapid reaction
zn - quite rapid reaction
fe - quite slow reaction

29
Q

reaction with dilute acid for lead and tin

A

react slowly with warm acid

30
Q

reaction with dilute acid for copper silver gold

A

No reaction

31
Q

Explain why aluminium can be used outdoors, for example for window frames, patio doors, even though it is quite high in the reactivity series

A

Aluminium is protected by a tough / impervious layer of aluminium
oxide

Aluminium reacts with the oxygen in the air to form an aluminium oxide layer.
Therefore it will not undergo reactions unless the oxide layer is removed.
This is why it can be used in window frames without corroding

32
Q

For a displacement reaction, harry used different starting temperatures
Explain why this did not affect his results

A

Because the change in temperature is not affected by the initial temperature

33
Q

Why was the highest rise in the temperature obtained with magnesium and copper sulphate (and not the acid reaction with zinc or iron)

A

Because mg and cu have the biggest different in reactivity compared to the different in reactivity with zn and cu, or fe and cu

34
Q

Describe how certain metals can be extracted using carbon

A

Because carbon is more reactive than certain elements.
It is able to displace those elements from their compounds, which as a result leaves that certain metal, extracted in its elemental form.

__________
Many metals have been oxidised by oxygen in the air to form their oxides
So to extract the metal from their oxides, the metal oxide must be reduced.
Because carbon is more reactive than certain elements.
It is able to displace those elements from their compounds, which as a result leaves that certain metal, extracted in its elemental form.

35
Q

Explain why gold is found in the earth as the metal itself

A

Because Gold is extremely unreactive (it does not easily react with other elements)

36
Q

what are most metals found as in the Earth

A

most metals are found as compounds

37
Q

Since most metals are found as compounds, what is needed to be done to extract the metal

A

most metals are found as compounds that require
chemical reactions to extract the metal.

38
Q

Displacement fact

A

A more reactive element will displace (push out/take the place of) a less reactive element from its compound

39
Q

explain why this is a displacement reaction

mg + iron oxide -> magnesium oxide + iron

A

Magnesium is more reactive than iron so it has displaced iron from its iron oxide compound

40
Q

magnesuim + sodium oxide —> magnesium oxide + sodium

Is this correct. why?

A

This is not correct. A displacement reaction cannot occur.
This is because magnesium is less reactive than sodium, therefore it cannot displace (reduce) sodium from the sodium oxide compound

41
Q

mg + iron oxide -> magnesium oxide + iron

in terms of oxygen, which atoms have been oxidised and reduced

A

Magnesium atoms have been oxidised because the magnesium atoms have gained oxygen

The iron atoms have been reduced because the iron atoms have lost oxygen

42
Q

What elements can reduce iron

A

Any element that is more reactive than iron can reduce iron.

43
Q

Why do we use carbon to reduce elements such as: zinc and iron

A

Any element that is more reactive than iron can reduce iron.
However, most of these elements are very expensive so in practice, carbon is used since it is extremely cheap.

44
Q

carbon + iron oxide —>

A

carbon + iron oxide —>carbon dioxide + iron

45
Q

symbol equation for the reduction of iron oxide using carbon

A

Fe2O3 + 3C —> 2Fe + 3CO

GCSE Chemistry (43 decks)

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