Brainscape's Knowledge GenomeTM

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


See full index

chem > redox and electrolysis > Flashcards

redox and electrolysis Flashcards

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

define the term “redox reaction”

A

a reaction where both oxidation and reduction take place

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

define the term ‘oxidation’

A

gain of oxygen
loss of electrons
loss of hydrogen

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

define the term ‘reduction’

A

loss of oxygen
gain of electrons
gain of hydrogen

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

define the term ‘oxidant’ and mention an example

A

oxidizing agent ( a substance which itself is reduced)
KMnO4 (potassium manganate) purple to colourless

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

define the term ‘reducing agent’ and mention a few examples

A

a substance which itself is oxidized
CO, CO2, H2, KI (colourless to orange brown)

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

define the term ‘electrolysis’

A

the breakdown of an ionic compound (1)
when molten or aqueous (1)
by the passage of electricity (1)

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

in an electrolysis cell, which two components are part of the ‘external circuit’

A

wire and electrodes

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

the cathode represents the ___ charge whereas the ____ represents the opposing charge

A

negative (1)
anode (1)

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

electrodes are…

A

rods that carry charge
or
rods that allow the passage of electricity

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

why must the electrolyte be molten or aqueous?

A

to have free moving ions to carry the charge

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

why must electrodes be made of graphite or platinum?

A

due to them being inert and good conductors

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

fluorine is _____ in colour at gas state

A

pale yellow

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

bromine is _____ in colour in gas state

A

orange brown

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

iodine is ____ in colour in gas state

A

purple

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

chlorine is ____ in colour in gas state

A

yellowish green

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

oxygen, hydrogen and nitrogen are ___ in colour in gas state

A

colourless

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

copper is a ___ metal (colour)

A

reddish brown

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

gold is a ___ metal (colour)

A

yellow

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

negatively charged ions move towards the ___

A

anode

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

positively charged ions move towards the ____

A

cathode

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

the current in electrolyte are (ions/electrons)

A

ions

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

the current in electrodes are (ions/electrons)

A

electrodes

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

why can ionic compounds conduct electricity when molten or aqueous?

A

due to free moving ions which carry charges

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

products of electrolysis of molten lead bromide

A

cathode: lead metal
anode: bromine gas
electrolyte: used up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

products of the electrolysis of molten calcium iodide

A

cathode: calcium metal
anode: iodine gas
electrolyte: used up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

give the observations seen after the electrolysis of molten zinc chloride

A

deposition of silvery grey metal at cathode
bubbles of yellowish green gas at anode
bulb lights up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

give the products of the electrolysis of conc. aqueous sodium chloride

A

cathode: hydrogen gas
anode: chlorine gas
electrolyte: sodium hydroxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

give the products and observations of the electrolysis of dilute copper sulfate

A

products
cathode: copper metal
anode: oxygen gas
electrolyte: sulfuric acid

observations
deposition of reddish brown metal at cathode
bubbles of colourless gas at anode
bulb lights up
blue colour of electrolyte fades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

define the term ‘electroplating’

A

a process where a thin layer of one metal is put on top of another object by electrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

give two uses of electrolysis

A
  1. protects metal from corrosion (rusting)
  2. gives an attractive and shiny appearance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

the object being electroplated is always the (cathode/anode)

A

cathode

32
Q

the plating metal is always the (cathode/anode)

A

anode

33
Q

the electrolyte in electroplating should always be

A

solution of the plating metal’s ionic compound

34
Q

how to electroplate a spoon with silver (mention cathodes, anodes and electrolyte)

A

cathode: spoon
anode: silver
electrolyte: silver nitrate (or any ionic compound of silver)

35
Q

why must an object be cleaned with sandpaper before electroplating?

A

to remove dirt or grease for a perfect coating

36
Q

how to achieve uniform coating during electroplating?

A

by rotating and fully immersing the object being electroplated in the electrolyte

37
Q

define the term ‘insulator’

A

a substance that resists the flow of current, and doesnt have any free moving electrons

38
Q

define the term ‘conductor’

A

a substance that allows electricity to flow through it, and has free moving electrons

39
Q

give 2 examples of insulators

A

plastic, wood, paper, glass, etc.

40
Q

give 2 examples of conductors

A

metals, graphite, etc.

41
Q

define the term ‘ore’

A

rock which a metal is naturally created and found in

42
Q

what method is used to extract the most reactive metals?

A

electrolysis

43
Q

what method is used to extract metals below carbon (in the reactivity series)

A

heating with carbon in a blast furnace

44
Q

how are least reactive metals found?

A

native, only need purification

45
Q

bauxite is the ore of (aluminum/iron)

A

aluminum

46
Q

bauxite consists of alumina which has a molecular formula of ___ and an impurity which is ___

A

Al2O3
Fe2O3 (iron oxide)

47
Q

what step is taken to remove impurities from bauxite?

A

crush the ore and mix with sodium hydroxide

48
Q

molten aluminium is collected at the (bottom graphite lining/anode graphite rods)

A

bottom graphite lining

49
Q

give molten cryolite’s molecular formula

A

Na3AlF6

50
Q

why do we dissolve alumina in molten cryolite?

A
  1. dec. mp. from 2040°C to 900° which saves time, cost and energy
  2. improves electrical conductivity of electrolyte
51
Q

what is seen in the cathode lining after the electrolysis of alumina?

A

aluminum metal (molten)

52
Q

after the electrolysis of alumina, what gases are present in the anode

A

oxygen gas (from Al2O3)

CO (incomplete combustion of graphite at anode)

CO2 (complete combustion of graphite at anode)

F2 (from cryolite)

53
Q

why must the anode be replaced periodically?

A

carbon anode ‘burn away’
due to complete and incomplete combustion reactions of hot carbon with oxygen
(producing CO and CO2)

54
Q

name 4 uses of aluminum and what properties of aluminium allow it to be suitable for each use

A
  1. aircraft bodies: low density, high tensile strength
  2. food/drink cans: nontoxic, non porous protective oxide layer that makes it resistant to corrosion
  3. saucepans: nontoxic, non porous protective oxide layer that makes it resistant to corrosion + high mp. + good conductor of heat
  4. overhead cables: high electrical conductivity, low density
55
Q

why do overhead cables use a steel core

A

to strengthen the cable (which prevents sagging)

56
Q

what is irons ore

A

hematite

57
Q

what does the ore hematite consist of

A

iron oxide and silicon oxide

58
Q

list 5 raw materials needed for the extraction of iron

A
  1. hematite (ore)
  2. carbon (coke/coal)
  3. limestone (CaCO3)
  4. water (coolant)
  5. hot air
59
Q

what step heats up the blast furnace (1000°C - 2000°C)

A

oxidation of carbon

60
Q

why does slag lay on top of molten iron

A

its less dense

61
Q

steel is an alloy of iron with?

A

carbon

62
Q

define the term alloy

A

mixture of two or more metals not chemically bonded/combined

63
Q

give 3 reasons for the production of alloys

A

inc hardness
more resistant to corrosion
improved appearance

64
Q

how to make alloys

A

by melting the metals and allowing them to cool together

65
Q

what increases the hardness of an alloy of steel

A

inc the percentage of carbon

66
Q

describe the composition of mild steel

A

99.75% iron
0.25% carbon

67
Q

give the used of mild steel

A

car bodies
machinery

68
Q

give the composition of hard steel

A

99% iron
1% carbon

69
Q

give the uses of hard steel

A

railway lines
building constructions
hammers
bridges

70
Q

give the composition of stainless steel

A

chromium
nickel
iron

71
Q

uses of stainless steel

A

cutlery
kitchen sinks
chemical plants
surgical tools

72
Q

brass composition

A

copper
zinc

73
Q

brass uses

A

instruments
door knockers

74
Q

bronze composition

A

copper
tin

75
Q

bronze uses

A

castings

76
Q

solder composition

A

50% lead
50% tin

77
Q

solder use

A

electrical conductors

chem (4 decks)

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