Brainscape's Knowledge GenomeTM

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


See full index

Chemistry Paper 1 > Chemical changes > Flashcards

Chemical changes Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

What is Electrolysis?

A

the breaking down of a substance using electricity. An electric current is passed through an electrolyte causing it to decompose.

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

What is an Electrolyte?

A

a molten or dissolved ionic compound

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

What is oxidation and reduction?

A

oxidation: loss of electrons
reduction: gain of electrons
occurs in electrolysis

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

What is the symbol for oxidation?

A

->e^-

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

What is the symbol for reduction?

A

+e^-

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

Where do the positive ions (cations) in the electrolyte move?

A

Towards the cathode (negative electrode) and are reduced (gains electrons)

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

Where do the Negative ions (anions) in the electrolyte move?

A

towards the anode (positive electrode) and are oxidised (lose electrons).

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

What is an electrochemical cell?

A

a circuit, made up of the anode, cathode, electrolyte, a power source and the wires that connect the two electrodes

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

If your electrolyte is a solution:

A

1) Get two inert electrodes, e.g. graphite
2)Place both electrodes into a beaker filled with your electrolyte.
3)Connect the electrodes to a power supply using crocodile clips and wires

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

If your Electrolyte is a Molten Ionic substance:

A

1) Put your solid ionic substance in a crucible
2)Heat the crucible with a bunsen burner until the solid’s molten.
3)Once the solid’s molten, dip two clean, inert electrodes into the electrolyte.
4) Connect electrodes to a power supply using wires and clips.

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

How many sets of ions are in Molten ionic solids?

A

2
1 positve and 1 negative

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

Why can’t ionic solid be electrolysed?

A

ions are in fixed positions and can’t move.

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

Why can molten ionic compounds be electrolysed?

A

ions can move freely and conduct electricity

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

What happens to positive metal ions at the cathode?

A

reduced to metal atoms

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

What happens to Negative ions at the anode?

A

are oxidised to atoms or molecules

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

How many sets of ions are there in Aqueous solutions? why?

A

4
2 positive and 2 negative
Electricity splits water into:
Hydrogen ions H+
Hydroxide ions OH-

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

What happens at the cathode during electrolysis of Aqueous solution?

A

If metal ion is LESS reactive than hydrogen, it will be the one that will gain electrons and turn to the atom.

If metal ion is MORE reactive than the hydrogen, it is the H+ ion that gains electrons and turns to hydrogen gas.

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

What happens at the anode during electrolysis of Aqueous solution?

A

If negative ion is above OH-, it will be the one turn to atom.

If negative ion is below OH-, the OH- turns to oxygen gas and water.

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

What are the four different ions a solution of copper contains?

A

Cu2+, So4 2-, H+ and OH-

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

What happens when you electrolyse copper sulfate solution with inert electrodes?

A

Copper is less reactive than hydrogen, so copper metal is produced at the cathode.

Sulfate is below Hydroxide, so oxygen and water are produced at the anode.

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

What happens if you use copper electrodes in a solution of copper sulfate instead of inert electrodes?

A

Result is different.
the mass of the anode will decrease and the mass of the cathode will increase. This is because the copper is transfered from the anode to the cathode.

22
Q

How can you measure how the mass of your electrodes have changed?

A

finding the difference between the masses of the electrodes before and after the experiment.

23
Q

What is The pH scale?

A

a measure of how acidic or alkaline a solution is.

24
Q

What pH does a neutral substance have?

A

pH 7

25
Q

What makes a solution more or less acidic?

A

the concentration of hydrogen ions
as concentration of hydrogen ions increases, the pH decreases.

26
Q

What is an acid?

A

a substance with a pH of less than 7. Acids form H+ ions in water

27
Q

What is a Base?

A

a substance that reacts with an acid to produce salt and water.

28
Q

What is an Alkali?

A

a base that is soluble in water. All alkalis have a pH of more than 7 and they form OH- ions in water.

29
Q

What makes an alkaline solution have a higher pH?

A

higher concentration of OH- ions.

30
Q

What is an indicator?

A

a dye that changes colour depending on whether it’s above or below a certain pH.

31
Q

How do you use an indicator?

A

add a few drops to the solution you’re testing, then compare the colour the solutions goes to a pH chart for that indicator.

32
Q

What is a litmus indicator?

A

red in acidic solutions, purple in neutral solutions and blue in alkaline solutions

33
Q

What is a methyl orange indicator?

A

red in acidic solutions and yellow in neutral and alkaline solutions.

34
Q

What is a phenolphthalein indicator?

A

colourless in acidic or neutral solutions and pink in alkaline solutions.

35
Q

What is the reaction between an acid and a base called?

A

Neutralisation, produces salt and water.

36
Q

What happens when an acid neutralises a base (or vice versa)?

A

the products are neutral, i.e. they have a pH of 7.
concentration of hydrogen ions is equal to the concentration of hydroxide ions.

37
Q

How do Acids produce hydrogen ions in water?

A

All acids can ionise (or dissociate) in solution - that means splitting up to produce a hydrogen ion, H+ and another ion.

38
Q

What are strong acids?

A

ionise almost completely in water, i.e. a large proportion of the acid molecules dissociate to release H+ ions. Tend to have low pHs.

39
Q

What are weak acids?

A

do not fully ionise in solution, i.e. only a small proportion of the acid molecules dissociate to release H+ ions. pHs tend to be around 2-6

40
Q

How is a weak acid a reversable reaction?

A

only a few of the acid particles release H+ ions, equilibrium lies well to the left

41
Q

What is the difference between Acid strength and Acid concentration?

A

strength tells you what proportion of the molecules ionise in water but concentration measures how much acid there is in a litre of water. Basicslly how watered down your acid is.

42
Q

How does changing the concentration of an Acid affect its pH?

A

if concentration of H+ ions increases by a factor of 10, the pH decreases by 1.

43
Q

What is formed when acids react with bases?

A

A salt is formed. Salts are ionic compounds.

44
Q

What does Acid + Metal oxide produce?

A

Salt + water

45
Q

What does Acid + Metal hydroxide produce?

A

Salt + water

46
Q

What does Acid + Metal produce?

A

Salt + hydrogen

47
Q

How do you test for hydrogen?

A

use a lighted splint.
Hydrogen makes squeaky pop sound.

48
Q

What does Acid + Metal carbonate produce?

A

Salt + water + carbon dioxide

49
Q

How to test for carbon dioxide?

A

by bubbling it through limewater.
if gas is carbon dioxide, the limewater will turn cloudy.

50
Q

How to make a pure, dry sample of an insolube salt?

A

use precipitation reaction.
pick the right two soluble salts and react them together to get your insoluble salt.

51
Q

How to make soluble salts?

A

reacting an acid that contains one of the ions you want in the salt with an insoluble base that contains the other ion you need.

Chemistry Paper 1 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions