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GCSE Chemistry > Chemical reaction > Flashcards

Chemical reaction Flashcards

1
Q

\define oxidation (in terms of electrons)

A

Oxidation is the loss of electrons

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2
Q

define reduction (in terms of electrons)

A

reduction is the gain of
electrons

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3
Q

Mg —-> Mg2+ + 2e-

Describe what has happened

A

Magnesium, loses two electrons to form the Magnesium ion (mg2+ ion)

The magnesium atom has been oxidised as it has lost electrons

This is a oxidation reaction because the magnesium atom has lost electrons

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4
Q

S + 2e- —> S2-

Describe what has happened

A

Sulfur has gained two electrons and formed the sulfide ion

The sulfur atom has been reduced as it has gained electrons

This is a reduction reaction has the sulfur atom has gained electrons

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5
Q

OIL RIG

A

Oxidation is loss of electrons
Reduction is gain of electrons

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6
Q

Identify in the reaction below which element (species) has been oxidised and which has been reduced

zinc + copper sulfate –> zinc sulfate + copper

Zn + CuSO4 –> ZnSO4 + Cu

A

The zinc atom has been oxidised as it has lost two electrons (oxidation is loss of electrons)

The copper ion has been reduced as it has gained two electrons (reduction is gain of electrons)

(We start with the zinc atom, Zn and we end up with the Zinc ion , Zn2+
In order for this to happen, the zinc atom must have lost two electrons, therefore the zinc atom has been oxidised.

We start with the copper ion, Cu2+ and end up with the copper atom, Cu. In order for this to happen, the copper must have gained two electrons, therefore it has been reduced.

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7
Q

zinc + copper sulfate –> zinc sulfate + copper

Zn + CuSO4 –> ZnSO4 + Cu

what type of reaction is this

A

a displacement reaction

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8
Q
  • write ionic equations for displacement reactions

Zn + CuSO4 –> ZnSO4 + Cu

A

Zn + Cu2+ + SO42- —> Zn2+ A-SO42- + Cu

Zn + Cu2+ —–> Zn2+ + Cu

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9
Q

aq meaning

A

aq = aqueous solution - dissolved in water

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10
Q

What do acids produce in aqueous solutions

A

In aqueous solutions, acids produce hydrogen ions (H+ ions)

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11
Q

Write an equation to show how hydrochloric acid ionises in water
(showing hydrochloric acid in aqueous solution)

A

HCl (aq) –> H+(aq) + Cl- (aq)

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12
Q

Describe what has happened
HCl (aq) –> H+(aq) + Cl- (aq)

A

This is how hydrochloric acid ionises in water

The molecule has split and released H+ (hydrogen ion)
The chloride ion (Cl-) has also been made (produced)

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13
Q

Write an equation to show how sulphuric acid ionises in water
(showing sulfuric acid in aqueous solution)

And describe what has happened

A

H2SO4(aq) –> 2H+(aq) + SO42-(aq)

This is how sulfuric acid ionises in water

The molecule has split and released H+ (hydrogen ion)
The sulfate ion (SO42-) has also been made (produced)

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14
Q

Write an equation to show how nitric acid ionises in water
(showing nitric acid in aqueous solution)

And describe what has happened

A

HNO3(aq) —> H+(aq) NO3-(aq)

This is how nitric acid ionises in water

The molecule has split and released H+ (hydrogen ion)

The nitrate ion (NO3-) has also been made (produced)

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15
Q

What is an acid

A

A substance that releases H+ ions when in a solution

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16
Q

What is a base

A

Chemicals which can neutralise acids producing a salt and water

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17
Q

Examples of bases

A

Metal oxides
Metal hydroxides

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18
Q

Examples of bases

A

Copper oxide
Iron (III) hydroxide
Sodium hydroxide

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19
Q

Explain why Copper oxide
Iron (III) hydroxide and Sodium hydroxide are bases (are called bases)

A

All of these are bases because they can neutralise acids producing a salt and water

20
Q

What is an alkali

A

Bases which are soluble in water are called alkalis

21
Q

Out of Copper oxide
Iron (III) hydroxide
Sodium hydroxide

which ones are bases only and which ones are a base and an alkali.
Explain your choices

A

Copper oxide and Iron (III) hydroxide are both insoluble in water, so these are bases only

Sodium Hydroxide is soluble in water, so sodium hydroxide is both a base and an alkali

22
Q

What do alkalis produce in aqueous solutions

A

In aqueous solutions, alkalis produce hydroxide ions (OH- ions) –

  • (alkalis are substances that release OH- ions when added to water)
23
Q

Write an equation to show how sodium hydroxide ionises in water
(showing sodium hydroxide in aqueous solution)

And describe what has happened

A

NaOH(aq) –> Na+ (aq) + OH- (aq)

The sodium hydroxide is splitting, producing the sodium ion Na+ and the hydroxide ion OH-

The molecule has split and released OH- (hydroxide ion)
The Na+ (sodium ion) has also been made (produced)

24
Q

What is the pH scale

A

The pH scale, from 0 to 14, is a measure of the acidity or alkalinity
of a solution,

25
Q

What does the pH scale measure

A

The pH scale, from 0 to 14, is a measure of the acidity or alkalinity
of a solution,

26
Q

What pH’s do acids, neutral solutions and alkalis have have

A

Acids have a pH between 0 and 6
Solutions with a pH of 7 are neutral
Alkaline solutions have a pH between 8 and 14

27
Q

How can you determine the pH of a solution (how can the pH of a solution be measured)

A

We can determine the pH of a solution using either a pH probe or Universal Indicator

28
Q

How does a pH probe work

A

A pH probe determines the pH electronically

29
Q

How does Universal Indicator work

A

Universal indicator changes colour, depending on whether a solution is acid, alkali or neutral

(red, orange, yellow - acid)
green -neutral
blue, purple (alkali)

increasing in numbers
yellow - weak acid
blue - weak alkali
red - strong acid
purple - strong alkali

30
Q

What does the different colours of the Universal Indicator show

A

They show whether a solution is acid, alkali or neutral

Green shows a neutral solution (pH 7)
Very acidic solutions produce a red colour
A purple colour shows a very alkaline solution

31
Q

General equation for neutralisation

A

Acid + Alkali –> Salt + Water

32
Q

Describe what happens during neutralisation

A

In neutralisation reactions, when an acid reacts with an alkali, the hydrogen ions react with the hydroxide ions to produce water

33
Q

Write the (ionic) equation for neutralisation

A

H+ (aq) + OH- (aq) —> H2O (l)

34
Q

write the ionic equation for the reaction between hydrochloric acid and sodium hydroxide
explain you choice

A

The reaction between hydrochloric acid and sodium hydroxide is a neutralisation reaction

The ionic equation for a neutralisation reaction is H+ (aq) + OH- (aq) —> H2O (l)

therefore the ionic equation for the reaction between HCL and NaOH is also H+ (aq) + OH- (aq) —> H2O (l)

35
Q

H+ (aq) + OH- (aq) —> H2O (l)

explain this

A

In neutralisation reactions, when an acid reacts with an alkali, the hydrogen ions react with the hydroxide ions to produce water

H+ ions from the acid
OH- ions from the alkali

36
Q

What can metals such as potassium, sodium, zinc etc. do to hydrochloric acid

A

These metals are more reactive than hydrogen
Therefore they can displace hydrogen from acids

37
Q

is this a displacement reaction explain why

H2SO4 + Mg —> MgSO4 + H2

A

sulfuric acid + magnesium –> magnesium sulphate + hydrogen

Yes, it is a displacement reaction.
In a displacement reaction, a more reactive element will displace (takes the place of) a less reactive element from its compound

The magnesium is more reactive than the hydrogen, so it has displaced the hydrogen from the sulfuric acid

38
Q

Explain why there is no reaction between copper and hydrochloric acid

A

No reaction occurs because copper is less reactive than hydrogen, therefore it cannot displace hydrogen from the hydrochloric acid. Therefore no displacement reaction occurs, which means there is no chemical reaction between copper and hydrochloric acid

39
Q

Magnesium sulfate is an example of a ____

A

Magnesium sulfate is an example of a salt

40
Q

general equation for acid and metal

A

Acid + Metal –> Salt + Hydrogen

41
Q

what type of salts does hydrochloric acid produce

A

Hydrochloric acid produces chloride salts

42
Q

what type of salt does sulfuric acid produce

A

Sulfuric acid produces sulfate salts

43
Q

what type of salt does nitric acid produce

A

nitric acid produces nitrate salts

44
Q

hydrochloric acid + magnesium —>

A

hydrochloric acid + magnesium —? magnesium chloride + hydrogen

45
Q

hydrochloric acid + _______ —> magnesium chloride + hydrogen

A

hydrochloric acid + magnesium –> magnesium chloride + hydrogen

46
Q

Explain why magnesium reacts more vigorously than zinc or iron, when the three metals react with hydrochloric acid

A

Because magnesium and hydrogen have the biggest difference in reactivity compared to the difference in reactivity with zinc and hydrogen, or iron and hydrogen.

(IRON IS ONLY SLIGHTLY MORE REACTIVE THAN HYDROGEN, MEANING THAT A REACTION BETWEEN IRON AND ACIDS WILL BE A SLOW REACTION)

This means that magnesium can easily displace hydrogen from hydrochloric acid (acids)

47
Q

describe and compare the reactions of magnesium, zinc and iron with acids

A

magnesium reacts rapidly with acids
zinc reacts fairly rapidly with acids
iron reacts fairly slowly with acids

GCSE Chemistry (43 decks)

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