Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GCSE - Chemistry > Topic 3 - Chemical Changes > Flashcards

Topic 3 - Chemical Changes Flashcards

1
Q

Which ions make aqueous solutions acidic?

A

Hydrogen ions (H⁺)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which ions make aqueous solutions alkaline?

A

Hydroxide ions (OH⁻)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the pH scale?

A

Ranges from 0-14 and measures acidity of alkalinity of a solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the pH ranges for acids and alkalis? What’s the pH of a neutral solution?

A

Acid - less than pH7
Neutral - pH7
Alkali - greater than pH7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can be used to measure pH?

A

Universal indicator

pH probe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What colour is phenolphthalein in acid and alkali?

A

Acid - colourless

Alkali - pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What colour is methyl orange in an acid and alkali?

A

Acid - red

Alkali - yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

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

A

Acid - turns red

Alkali - stays blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

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

A

Acid - stays red

Alkali - turns blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

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

A

Colour of solution matched to pH colour chart. Subjective as people can disagree with which colour matches.

Doesn’t provide exact pH value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Acid X has a pH of 1. What can you say about the concentration of hydrogen ions in acid X?

A

High concentration of hydrogen ions - strong acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Alkali Y has pH of 8.5. What can you say about the concentration of hydroxide ions in alkali Y?

A

Low concentration of hydroxide ions - weak alkali

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If pH decreases by 1 unit, what happens to the concentration of hydrogen ions?

A

The hydrogen ion concentration increases by a factor of 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a neutralisation reaction? What happens during an acid-alkali neutralisation reaction?

A

A reaction between an acid and a base.

H⁺ ions from acid react with OH⁻ ions from alkali to form water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What’s the ionic equation for a neutralisation reaction?

A

H⁺ (aq) + OH⁻ (aq) -> H ₂O (l)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do the terms concentrated and dilute mean?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does strength of an acid refer to?

A

Wether the acid will completely dissociate in water or not

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

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

A

Weak acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a base?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

True or false? ‘Alkalis are insoluble bases’

A

FALSE

Alkalis are soluble bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the products when an acid reacts with metal?

A

Salt and hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

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

A

Salt and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

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

A

Salt and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

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

A

Salt, water and carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why are metal oxides normally bases rather than alkalis?
Metal oxides are normally insoluble | Alkalis are soluble
26
What is the name of the salt formed from magnesium and sulfuric acid?
Magnesium sulfate
27
What is the name of the salt formed from zinc oxide and nitric acid?
Zinc nitrate
28
What is the name of the salt formed from calcium carbonate and hydrochloride acid?
Calcium chloride
29
Describe the chemical test for hydrogen
Insert a lit splint into test tube of gas | A ‘squeaky pop’ will be heard if hydrogen is present
30
Describe the chemical test for carbon dioxide
Bubble gas through limewater | Limewater turns cloudy if carbon dioxide is present
31
What is limewater?
Calcium hydroxide
32
When a so,bule salt is prepared from an acid and an insoluble reactant, why is excess of the insoluble reactant added?
To ensure all the acid reacts
33
When a soluble salt is prepared from an acid and an insoluble reactant, how and why is excess reactant removed?
By filtration to leave a pure solution of the salt
34
What method must be used to prepare a salt from an acid and a soluble reactant? Why?
Titration Both reactants are soluble - a titration allows you to combine the reactants exactly and avoid adding excess of either reactant as would be hard to remove.
35
Name the method that could be used to prepare a sample of soluble copper sulfate from insoluble copper oxide and sulfuric acid?
Filtration
36
What 3 steps are required when producing a pure dry salt from an acid and alkali?
Complete the titration to find the volume of acid that reacts exactly with a set volume of alkali. Use results to mix acid and alkali in correct proportions Evaporate water leaving pure dry salt crystals
37
Describe how to carry out an acid-alkali titration.
Use pipette - add measured vol of acid to conical flask + add few drops of indicator. Place on white tile. Fill burette with alkali, noting initial vol. Add alkali to flask and find the end point - where indicator first changes colour. Repeat adding alkali drop by drop and swirling glass constantly to mix. Récord final vol in burette. Repeat.
38
Most common chlorides are soluble. What are the 2 exceptions?
Silver chloride and lead chloride are insoluble
39
True or false? ‘All nitrates are soluble’
TRUE
40
Fill in the gap: ‘all common sodium, potassium and ammonium salts are ____’
Soluble
41
Most common surfaces are soluble, what are the 3 exceptions?
Lead sulfate, calcium sulfate and barium sulfate are insoluble.
42
Most common carbonates and hydroxides are insoluble, what are the 3 exceptions?
The carbonate/hydroxides of sodium, potassium and ammonium are soluble.
43
What salt is produced when lead reacts with sulfuric acid? Will a precipitate form?
Lead sulfate | A precipitate will form because lead sulfate is insoluble.
44
How could you prep a pure dry sample of an insoluble salt?
Mix 2 solutions required Filter mixture using filter paper Residue is insoluble salt Wash with distilled water and leave to dry
45
What is an electrolyte?
An ionic compound in its molten or aqueous state.
46
Why can an electrolyte carry charge?
An ionic compound in its molten or aqueous state has mobile ions which can carry charge.
47
What is electrolysis?
A process which uses electrical energy to decompose electrolytes.
48
What is the cathode and anode?
Cathode - negative electrode | Anode - positive electrode
49
What happens at the cathode during electrolysis?
Cations (+ ions) gain electrons to form their elements
50
Name the processes that occur at each electrode during electrolysis
Anode (+) = oxidation | Cathode (-) = reduction
51
Where do charged ions in the electrolyte move to during electrolysis?
Cations (+ ions) move towards the cathode | Anions (- ions) move towards the anode
52
What happens at the anode during electrolysis?
Anions (- ions) lose electrons to form their elements
53
What is formed at each electrode in electrolysis?
Positive electrode: non metal | Negative electrode: metal or hydrogen
54
How can you predict whether a metal or hydrogen will form at the negative electrode?
If hydrogen is above the metal in the reactivity series, metal will form. If metal is more reactive than hydrogen p, hydrogen will form.
55
What is formed at each electrode during the electrolysis of copper chloride solution?
+ electrode = chlorine | - electrode = copper
56
What is formed at each electrode during the electrolysis of sodium sulfate solution?
+ electrode = oxygen | - electrode = hydrogen
57
What is formed at each electrode during the electrolysis of molten lead bromide?
+ electrode = bromine | - electrode = hydrogen
58
Predict what will be formed at each electrode during the electrolysis of molten zinc chloride
+ electrode = chlorine | - electrode = zinc
59
What is formed at each electrode during the electrolysis of sodium chloride solution?
+ electrode = chlorine | - electrode = hydrogen
60
What is formed at each electrode during the electrolysis of water acidified with sulfuric acid?
+ electrode = oxygen | - electrode = hydrogen
61
What are the half equations for the reactions occurring at the cathode and anode during the electrolysis of copper chloride?
Anode: 2Cl⁻ -> Cl ₂ + 2e⁻ Cathode: Cu²⁺ + 2e⁻ -> Cu
62
What does oxidation mean in terms of electrons?
Loss of electrons
63
What does reduction mean in terms of electrons?
Gain of electrons
64
Describe how electrolysis of copper sulfate can be used to purify copper
Place 2 copper electrodes in copper sulfate solution. Anode should be impure copper + cathode pure copper. Connect to power supply. Copper in impure anode pulled towards cathode to form pure copper. Impurities form as sludge below anode. Cu²⁺ ions from copper sulfate remain in solution.

GCSE - Chemistry (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions