Define oxidation and reduction in terms of oxygen.

Oxidation is the addition of oxygen to an element or compound. Reduction is the removal of oxygen from an element or compound. Both occur simultaneously in a redox reaction.

2Cu + O 2 → 2CuO Which substance has been oxidised in this reaction, and why?

Copper (Cu) has been oxidised because oxygen has been added to it. The product copper(II) oxide (CuO) is a metal oxide formed by the direct reaction of copper with oxygen.

When sodium reacts with oxygen, the ion formed from oxygen has the symbol ________ and is correctly named the ________ ion.

When sodium reacts with oxygen, the ion formed from oxygen has the symbol O 2- and is correctly named the oxide ion. (Writing 'oxygen ion' does not score exam marks: the correct term is 'oxide ion.')

True or False? In a redox reaction, oxidation and reduction occur as separate, consecutive steps: first one happens, then the other.

False. Oxidation and reduction are simultaneous : they occur at the same time in the same reaction. You cannot have one without the other.

ZnO + C → Zn + CO The substance that is reduced is ________ because it ________ oxygen. The substance that is oxidised is ________ because it ________ oxygen.

The substance that is reduced is zinc oxide because it loses oxygen. The substance that is oxidised is carbon because it gains oxygen.

CuO + C → Cu + CO 2 . A student writes: 'Copper loses oxygen and is reduced. ' Why does this response lose marks, and what should they write instead?

The student has named the wrong substance. You must say ' Copper oxide loses oxygen and is reduced,' not 'copper.' Copper is the product after reduction; it cannot lose oxygen. The subject must be the compound that holds the oxygen before the reaction.

What does the reactivity series rank metals by, and what determines a metal's position at the atomic level?

The reactivity series ranks metals by their tendency to lose electrons and form positive ions. A metal is more reactive if its outer electron is further from the nucleus, creating a weaker attraction between the nucleus and the outer electron, so the outer electron is more easily lost .

Complete the reactivity series (most to least reactive): __ > Na > Li > __ > Mg > __ > C > Zn > __ > H > __ > Ag > Au.

The reactivity series (most to least reactive) is: K > Na > Li > Ca > Mg > Al > C > Zn > Fe > H > Cu > Ag > Au.

What are the products when calcium reacts with cold water, and magnesium reacts with steam?

Ca + 2H 2 O (l) → Ca(OH) 2 + H 2 : calcium hydroxide and hydrogen . Mg + H 2 O (g) → MgO + H 2 : magnesium oxide and hydrogen . (Steam gives the oxide, not the hydroxide.)

True or False? Aluminium does not react with water or dilute acid because it is low on the reactivity series.

False. Aluminium is high on the reactivity series but reacts slowly with dilute acids and not with cold water because it has a protective oxide layer (Al 2 O 3 ) on its surface. The reactivity series describes general trends, not absolute rules.

Why are carbon and hydrogen included in the reactivity series even though they are non-metals?

Hydrogen marks the boundary: metals above H displace it from water or acids; metals below H do not react with dilute acids. Carbon is included as a cheap reducing agent: metals below carbon can be extracted by heating their oxide with carbon; metals above carbon require electrolysis.

Mg + CuSO 4 → ________ + ________ In this displacement reaction, ________ is displaced from solution and ________ dissolves into solution.

Mg + CuSO 4 → MgSO 4 + Cu In this displacement reaction, copper is displaced from solution and magnesium dissolves into solution.

True or False? In the thermite reaction, aluminium displaces iron from iron(III) oxide because aluminium is more reactive than iron.

True. Since aluminium is above iron in the reactivity series, it displaces iron from its oxide: Fe 2 O 3 + 2Al → 2Fe + Al 2 O 3 . The reaction is highly exothermic and produces molten iron.

An experiment reacting metals with acids to produce a tmepreature change is set up. What variables must be controlled?

Use the same volume and concentration of acid for each metal Use the same mass of each metal Ensure each trial starts at the same temperature Stating specific values (e.g. 25 cm³ of 1 mol/dm³ acid, 5 g of metal) shows the variables are controlled.

True or False? When comparing metal reactivities by temperature change with acid, you only need to record the final temperature of the acid.

False. The starting temperature must also be recorded. Temperature change = final temperature − starting temperature. Without the starting temperature, no valid comparison can be made.

Define ore and explain how a metal's position in the reactivity series determines its method of extraction.

An ore is a rock containing enough of a metal compound to make extraction worthwhile. Metals above carbon in the reactivity series must be extracted by electrolysis (too reactive to reduce with carbon). Metals below carbon can be extracted by heating their oxide with carbon .

Name the ores of iron and aluminium , and explain why metals such as gold and platinum are found as uncombined elements in the Earth's crust.

Iron ore is haematite ; aluminium ore is bauxite . Gold and platinum are found as uncombined ( native ) metals because they are so unreactive that they do not form compounds readily, so they occur as pure elements.

Complete the word equation for extraction by reduction: ________ oxide + carbon → ________ + ________ In this reaction, the metal oxide is ________ because it ________ oxygen.

Metal oxide + carbon → metal + carbon dioxide The metal oxide is reduced because it loses oxygen.

True or False? Aluminium requires electrolysis for extraction simply because it is a reactive metal. Any reactive metal must be extracted by electrolysis.

False. The specific reason aluminium requires electrolysis is that it is more reactive than carbon , so it cannot be reduced by heating its oxide with carbon. The comparison to carbon is essential: metals above carbon need electrolysis; metals below carbon can be reduced cheaply.

Why is the extraction of aluminium by electrolysis expensive , and why must you specify 'molten' aluminium oxide rather than a solution?

Electrolysis is expensive because it requires large amounts of electrical energy (writing 'heat' does not score the mark). The aluminium oxide must be molten (not dissolved in solution) because pure aluminium oxide does not dissolve readily in water. Saying 'electrolysis of a solution' loses the mark.

In the electrolysis of aluminium oxide, why must the carbon (graphite) positive electrodes be continually replaced ?

Oxygen is produced at the positive electrode (anode). This oxygen reacts with the carbon electrode to form carbon dioxide . The electrode therefore burns away and must be replaced.

What does OIL RIG stand for?

OIL RIG stands for O xidation I s L oss (of electrons), R eduction I s G ain (of electrons). Both definitions refer explicitly to electrons: "reduction is gain" alone is insufficient.

In the reaction Fe + CuSO 4 → FeSO 4 + Cu, which species is oxidised and which is reduced?

Iron atoms (Fe) are oxidised: they lose two electrons to form Fe 2+ ions. Copper(II) ions (Cu 2+ ) are reduced: they gain two electrons to form Cu atoms.

In a half equation: Electrons appear as ________ of the equation when the species is oxidised, and as ________ when it is reduced.

In a half equation: Electrons appear as products of the equation when the species is oxidised (e.g. Fe → Fe²⁺ + 2e⁻), and as reactants when it is reduced (e.g. Cu²⁺ + 2e⁻ → Cu).

True or False? When magnesium reacts with hydrochloric acid, magnesium atoms are oxidised because they lose oxygen.

False. Magnesium atoms are oxidised because they lose electrons (to form Mg²⁺). The oxygen-based definition does not apply here; this is an electron transfer reaction, so OIL RIG must be used.

In the reaction between magnesium and hydrochloric acid, what is reduced and why?

The H⁺ ion is reduced — each H⁺ ion gains one electron to form a neutral hydrogen atom. You must identify the specific ion (H⁺), not just "hydrogen."

When chloride ions are discharged at the anode during electrolysis, they form ________ molecules — not individual Cl atoms.

When chloride ions are discharged at the anode during electrolysis, they form Cl 2 molecules — not individual Cl atoms.

Write the half equation for chloride ions being discharged at the anode during electrolysis.

2Cl⁻ → Cl 2 + 2e⁻ Chloride ions form Cl 2 molecules — writing Cl instead of Cl 2 omits the diatomic nature of chlorine and is a commonly penalised error.

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Reactivity of Metals (AQA GCSE Combined Science: Trilogy: Chemistry): Flashcards

Exam code: 8464

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Define oxidation and reduction in terms of oxygen.

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Cards in this collection (28)

Define oxidation and reduction in terms of oxygen.
Oxidation is the addition of oxygen to an element or compound. Reduction is the removal of oxygen from an element or compound. Both occur simultaneously in a redox reaction.
2Cu + O₂ → 2CuO
Which substance has been oxidised in this reaction, and why?
Copper (Cu) has been oxidised because oxygen has been added to it. The product copper(II) oxide (CuO) is a metal oxide formed by the direct reaction of copper with oxygen.
When sodium reacts with oxygen, the ion formed from oxygen has the symbol ________ and is correctly named the ________ ion.
When sodium reacts with oxygen, the ion formed from oxygen has the symbol O^2- and is correctly named the oxide ion.
(Writing 'oxygen ion' does not score exam marks: the correct term is 'oxide ion.')
True or False?
In a redox reaction, oxidation and reduction occur as separate, consecutive steps: first one happens, then the other.
False.
Oxidation and reduction are simultaneous: they occur at the same time in the same reaction. You cannot have one without the other.
ZnO + C → Zn + CO
The substance that is reduced is ________ because it ________ oxygen.
The substance that is oxidised is ________ because it ________ oxygen.
The substance that is reduced is zinc oxide because it loses oxygen.
The substance that is oxidised is carbon because it gains oxygen.
CuO + C → Cu + CO₂.
A student writes: 'Copper loses oxygen and is reduced.
' Why does this response lose marks, and what should they write instead?
The student has named the wrong substance. You must say 'Copper oxide loses oxygen and is reduced,' not 'copper.'
Copper is the product after reduction; it cannot lose oxygen. The subject must be the compound that holds the oxygen before the reaction.
What does the reactivity series rank metals by, and what determines a metal's position at the atomic level?
The reactivity series ranks metals by their tendency to lose electrons and form positive ions. A metal is more reactive if its outer electron is further from the nucleus, creating a weaker attraction between the nucleus and the outer electron, so the outer electron is more easily lost.
Complete the reactivity series (most to least reactive):
__ > Na > Li > __ > Mg > __ > C > Zn > __ > H > __ > Ag > Au.
The reactivity series (most to least reactive) is:
K > Na > Li > Ca > Mg > Al > C > Zn > Fe > H > Cu > Ag > Au.
What are the products when calcium reacts with cold water, and magnesium reacts with steam?
Ca + 2H₂O (l) → Ca(OH)₂ + H₂: calcium hydroxide and hydrogen.
Mg + H₂O (g) → MgO + H₂: magnesium oxide and hydrogen.
(Steam gives the oxide, not the hydroxide.)
True or False?
Aluminium does not react with water or dilute acid because it is low on the reactivity series.
False.
Aluminium is high on the reactivity series but reacts slowly with dilute acids and not with cold water because it has a protective oxide layer (Al₂O₃) on its surface. The reactivity series describes general trends, not absolute rules.
Why are carbon and hydrogen included in the reactivity series even though they are non-metals?
Hydrogen marks the boundary: metals above H displace it from water or acids; metals below H do not react with dilute acids.
Carbon is included as a cheap reducing agent: metals below carbon can be extracted by heating their oxide with carbon; metals above carbon require electrolysis.
Mg + CuSO₄ → ________ + ________
In this displacement reaction, ________ is displaced from solution and ________ dissolves into solution.
Mg + CuSO₄ → MgSO₄ + Cu
In this displacement reaction, copper is displaced from solution and magnesium dissolves into solution.
True or False?
In the thermite reaction, aluminium displaces iron from iron(III) oxide because aluminium is more reactive than iron.
True.
Since aluminium is above iron in the reactivity series, it displaces iron from its oxide:
Fe₂O₃ + 2Al → 2Fe + Al₂O₃.
The reaction is highly exothermic and produces molten iron.
An experiment reacting metals with acids to produce a tmepreature change is set up.
What variables must be controlled?
Use the same volume and concentration of acid for each metal
Use the same mass of each metal
Ensure each trial starts at the same temperature
Stating specific values (e.g. 25 cm³ of 1 mol/dm³ acid, 5 g of metal) shows the variables are controlled.
True or False?
When comparing metal reactivities by temperature change with acid, you only need to record the final temperature of the acid.
False.
The starting temperature must also be recorded.
Temperature change = final temperature − starting temperature.
Without the starting temperature, no valid comparison can be made.
Define ore and explain how a metal's position in the reactivity series determines its method of extraction.
An ore is a rock containing enough of a metal compound to make extraction worthwhile. Metals above carbon in the reactivity series must be extracted by electrolysis (too reactive to reduce with carbon). Metals below carbon can be extracted by heating their oxide with carbon.
Name the ores of iron and aluminium, and explain why metals such as gold and platinum are found as uncombined elements in the Earth's crust.
Iron ore is haematite; aluminium ore is bauxite. Gold and platinum are found as uncombined (native) metals because they are so unreactive that they do not form compounds readily, so they occur as pure elements.
Complete the word equation for extraction by reduction:
________ oxide + carbon → ________ + ________
In this reaction, the metal oxide is ________ because it ________ oxygen.
Metal oxide + carbon → metal + carbon dioxide
The metal oxide is reduced because it loses oxygen.
True or False?
Aluminium requires electrolysis for extraction simply because it is a reactive metal. Any reactive metal must be extracted by electrolysis.
False.
The specific reason aluminium requires electrolysis is that it is more reactive than carbon, so it cannot be reduced by heating its oxide with carbon. The comparison to carbon is essential: metals above carbon need electrolysis; metals below carbon can be reduced cheaply.
Why is the extraction of aluminium by electrolysis expensive, and why must you specify 'molten' aluminium oxide rather than a solution?
Electrolysis is expensive because it requires large amounts of electrical energy (writing 'heat' does not score the mark).
The aluminium oxide must be molten (not dissolved in solution) because pure aluminium oxide does not dissolve readily in water. Saying 'electrolysis of a solution' loses the mark.
In the electrolysis of aluminium oxide, why must the carbon (graphite) positive electrodes be continually replaced?
1. Oxygen is produced at the positive electrode (anode).
2. This oxygen reacts with the carbon electrode to form carbon dioxide.
3. The electrode therefore burns away and must be replaced.
What does OIL RIG stand for?
OIL RIG stands for Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
Both definitions refer explicitly to electrons: "reduction is gain" alone is insufficient.
In the reaction Fe + CuSO₄ → FeSO₄ + Cu, which species is oxidised and which is reduced?
Iron atoms (Fe) are oxidised: they lose two electrons to form Fe²⁺ ions.
Copper(II) ions (Cu²⁺) are reduced: they gain two electrons to form Cu atoms.
In a half equation:
Electrons appear as ________ of the equation when the species is oxidised, and as ________ when it is reduced.
In a half equation:
Electrons appear as products of the equation when the species is oxidised (e.g. Fe → Fe²⁺ + 2e⁻), and as reactants when it is reduced (e.g. Cu²⁺ + 2e⁻ → Cu).
True or False?
When magnesium reacts with hydrochloric acid, magnesium atoms are oxidised because they lose oxygen.
False.
Magnesium atoms are oxidised because they lose electrons (to form Mg²⁺). The oxygen-based definition does not apply here; this is an electron transfer reaction, so OIL RIG must be used.
In the reaction between magnesium and hydrochloric acid, what is reduced and why?
The H⁺ ion is reduced — each H⁺ ion gains one electron to form a neutral hydrogen atom. You must identify the specific ion (H⁺), not just "hydrogen."
When chloride ions are discharged at the anode during electrolysis, they form ________ molecules — not individual Cl atoms.
When chloride ions are discharged at the anode during electrolysis, they form Cl₂ molecules — not individual Cl atoms.
Write the half equation for chloride ions being discharged at the anode during electrolysis.
2Cl⁻ → Cl₂ + 2e⁻
Chloride ions form Cl₂ molecules — writing Cl instead of Cl₂ omits the diatomic nature of chlorine and is a commonly penalised error.

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