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Chemistry > Topic 3 - chemical changes > Flashcards

Topic 3 - chemical changes Flashcards

1
Q

Which ions make aqueous solutions acidic?

A

Hydrogen

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2
Q

Which ions make aqueous solutions alkaline?

A

Hydroxide

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3
Q

What is the pH scale?

A

It ranges from pH 0 to pH 14 and measures the acidity or alkalinity of a solution

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4
Q

What is the pH of a neutral solution?

A

7

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5
Q

What is the pH range for acids?

A

Less the pH 7

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6
Q

What is the range of pH for alkaline?

A

More than pH 7

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7
Q

What can be used to measure pH?

A

Universal indicator

pH probe

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8
Q

What colour is phenolphthalein in acid and alkali?

A

Acid - pink

Alkali - colourless

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9
Q

What colour is methyl orange ina an acid and an alkali?

A

Acid - red

Alkali - yellow

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10
Q

What colour is blue lit as paper in an acid and an alkali?

A

Acid - turns red

Alkali - stays blue

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11
Q

What colour is red litmus paper in an acid and an alkali?

A

Acid - stays red

Alkali - turns blue

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12
Q

Suggest a problem with using universal indicator to test the pH of a solution

A

It is quite subjecting

It won’t provide an exact value

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13
Q

What is the concentration of hydrogen ions like in a strong acid?

A

High

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14
Q

What is the concentration of hydroxide ions in strong alkali?

A

High

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15
Q

If pH decreases by one unit, what happens to the concentration hydrogen ions?

A

The hydrogen ion concentration increases by a factor of 10

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16
Q

What is a neutralisation reaction?

A

A reaction between an acid and a base

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17
Q

What is the ionic equation for a neutralisation reaction?

A

H + Oh -> H2O

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18
Q

What do the terms concentrated and dilute mean when talking about acid?

A

Concentrated acids have more moles of acid per unit volume of water than dilute acids

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19
Q

An acid only partially dissociates in what er p, what can be said about the strength of the acid?

A

It is a weak acid

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20
Q

What is a base?

A

Any substance that react with an acid to form salt and water only

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21
Q

Are alkalis insoluble bases?

A

No, they are soluble

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22
Q

What are the products when an acid reacts with a metal?

A

Salt and hydrogen

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23
Q

What are the products when an acid reacts with a metal oxide?

A

Salt and water

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24
Q

What are the products when an acid reacts with a metal hydroxide?

A

Salt and water

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25
Q

What are the products when an acid reacts with a metal carbonate?

A

Salt, water and carbon dioxide

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26
Q

Why are metal oxides normally bases rather than alkalis?

A

They are normally insoluble

Alkalis are soluble

27
Q

What is the name of the salt formed from magnesium and sulphuric acid?

A

Magnesium sulphate

28
Q

What is the name of the salt formed from zinc and nitric acid?

A

Zinc nitrate

29
Q

What is the name of the salt formed from calcium carbonate and hydrochloric acid?

A

Calcium chloride

30
Q

Describe the chemical test for hydrogen

A

Insert a lit splint into a test tube of gas

A ‘squeaky pop’ will be heard if hydrogen is present

31
Q

Describe the chemical test for carbon dioxide

A

Bubble the gas through limewater

Limewater turns cloudy is carbon dioxide is present

32
Q

When a soluble salt is prepared from an acid and an insoluble reactant, why is excess of the insoluble reactant added?

A

To ensure all the acid reacts

33
Q

When a soluble salt is prepared from an acid and an insoluble reactant, how and why is excess reactant removed?

A

By filtration

34
Q

What method must be used to prepare a salt from an acid and a soluble reactant?

35
Q

Name the method that could be used to prepare a sample of soluble copper sulphate from insoluble copper oxide and sulphuric acid?

A

Filtration

36
Q

What 3 steps are required when producing a pure dry salt from an acid and alkali?

A

Complete a titrations. To find the volume of acid that reacts exactly with a set volume of alkali
Use the results from the titration to mix the acid and alkali in the correct proportions
Evaporate the water from the solution, leaving pure dry salt crystals

37
Q

Most common chlorides are soluble. What are the two exceptions?

A

Silver chloride and lead chloride

38
Q

Are all nitrates soluble?

39
Q

Are all common sodium, potassium and ammonium salts soluble?

40
Q

Most common sulphate are soluble. What are the three exceptions?

A

Lead sulphate, calcium sulphate and barium sulphate

41
Q

Most common carbonates and hydroxides are insoluble. What are the three exceptions?

A

The carbonate/ hydroxides of sodium and ammonium

42
Q

What salt is produced when lead reacts with sulphuric acid?

A

Lead sulphate

43
Q

How could you prepare a pure, dry sample of an insoluble salt?

A

Mix the two solutions required to form the salt
Filter the mixture using filter paper
The residue of the filter paper is the insoluble salt
Wash the salt with distilled water and leave to dry

44
Q

What is an electrolyte?

A

An ionic compound in its molten or aqueous state

45
Q

Why can an electrolyte carry charge?

A

An ionic compound in its molten or aqueous state has Mobil earth ions which can carry charge

46
Q

What is electrolysis?

A

A process which used electrical energy to decompose electrolytes

47
Q

What is the cathode and anode?

A

Cathode - negative electrode

Anode - positive electrode

48
Q

Where do charged ions in the electrolyte move to during electrolysis?

A

Cations move towards the cathode

Anions move towards the anode

49
Q

What happens at the anode during electrolysis?

A

The anions lose electrons to form their elements

50
Q

What happens at the cathode during electrolysis?

A

Cations gain electrons to form their elements

51
Q

Name the processes that occur at each electrode during electrolysis

A

Anode - oxidation

Cathode - reduction

52
Q

What is formed at each electrode in electrolysis?

A

Anode : non-metal

Negative : metal or hydrogen

53
Q

How can you predict whether a metal or hydrogen will form at the negative electrode?

A

If hydrogen is above the metal in the reactivity series then the metal will form
If the metal is more reactive than hydrogen then hydrogen will form

54
Q

What is formed at each electrode during the electrolysis of copper chloride solution?

A

Anode: chlorine
Cathode: copper

55
Q

What is formed at each electrode during the electrolysis of sodium sulphate solution?

A

Anode: oxygen
Cathode: Hydrogen

56
Q

What is formed at each electrode during the electrolysis of molten lead bromide?

A

Anode: bromine
Cathode: hydrogen

57
Q

What will be formed at each electrode during the electrolysis of molten zinc chloride?

A

Anode: chlorine
Cathode: zinc

58
Q

What is formed at each electrode during the electrolysis of sodium chloride solution?

A

Anode: chlorine
cathode: hydrogen

59
Q

What I’d formed at each electrode during the electrolysis of water acidified with sulphuric acid?

A

Anode: oxygen
Cathode: Hydrogen

60
Q

What are the half equations for the reactions occurring at the cathode and anode during the electrolysis of copper chloride?

A

Anode: 2Cl- -> Cl2 + 2e-
Cathode: Cu2+ + 2e- -> Cu

61
Q

What does education mean in terms of electrons?

A

Loss of electrons

62
Q

What does reduction mean in terms of electrons?

A

Gain of electrons

63
Q

How can electrolysis of copper sulphate be used to purify copper?

A

Place 2 copper electrodes into copper sulphate solution
The anode should be impure copper and cathode should be pure
Connect to a power supple
The copper in the impure is pulled towards the cathode to form pure copper
Impurities form as sludge below the anode
Cu2+ ions from copper sulphate remain in solution

Chemistry (8 decks)

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