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Flashcards in Chemistry Deck (99):
1

What percentage is there of nitrogen in the air

78%

2

What percentage is there of argon in the air

0.9%

3

What percentage of co2 is there in the air

0.037%

4

What is wrong with the oxygen percentage test in which copper is heated up

There is air between the copper and the air in the gas syringe expands due to an next ease in temperature

5

How was the earths early atmosphere formed

Volcanic activity

6

What was the consistency of the earths early atmosphere

Mostly carbon dioxide

7

How many billion years was there intense volcanic activity to form the earths early atmosphere

1 billion

8

What gases other than co2 probably existed in the early atmosphere

Water vapour, ammonia, methane

9

How did the oceans get formed

The water vapour in the early atmosphere condensed because the earth cooled

10

Which to planets are believed to have early similar atmospheres compared to the early atmosphere of earth

Mars and Venus as their atmospheres consist mainly of carbon dioxide

11

Of they weren't there how can scientists know the consistency o the early atmosphere

Scientists had to gain information from other sources for example:
Volcanoes on other planets release high quantities of carbon dioxide

Nitrogen and iron compounds present in very old rocks that could only have formed in an ocygen free environment

12

How did the proportions of oxygen in the early atmosphere go up and the proportion of carbon dioxide go down

The proportion of oxigen went up because of photosynthesis by plants

Carbon dioxide went down because:
It was locked up in sedimentary rocks like limestone, and in fossil fuels like oil

It was absorbed by plants for photosynthesis

It dissolved in oceans

13

How is the level of the current atmospheres co2 increasing

We are burning fossil fuels and adding co2 into the air faster than it can be removed

14

How is the level of carbon dioxide maintained

Photosynthesis
Green plants all remove co2 from the air through photosynthesis

Combustion
Releases co2 into the air

Respiration
Releases co2 into the air

15

Steps of the carbon cycle

Respiration and combustion out co2 into the air

Photosynthesis takes co2 out of the air

Animals eat plants and release co2 back into the air

16

Ways humans are increasing the atmospheres co2 content

With more people we burn more fossil fuels for energy

When land is cleared for timber and farms there are fewer trees to remove co2 this is extra bad when we clear trees for farmland by burning them

17

One does not always get the calculated amount of product from a reaction because;

Reversible reactions may not go to completion

Some products may be lost when it's removed from the reaction mixture

Some of the reactants may react in an unexpected way

18

What is an example of conservation of mass

A precipitation reaction

19

Why is it easy to show conservation of mass in a precipitation reaction

All the reactants and products remain in the same sealed reaction container so it is easy to show the mass has not changed

20

What is copper sulphate

CuSO4

21

What is sodium hydroxide

NaOH

22

What colour precipitate does iron (II) produce

Green- turns brown when standing

23

What colour precipitate does iron (111)
Produce

Orangy brown

24

What colour precipitate does copper produce

Blue pale

25

What colour precipitate does zinc produce

White

26

4 features of acids

Have a low ph (1-6)

React with bases to form neutral compounds

Are corrosive when strong

Are irritant when weak

27

What is an indigestion remedy

An indigestion remedy contains a base like magnesium hydroxide which reacts to form a neutral compound and raises the oh of the stomach

28

What do you observe during a metal hydroxide and acid reaction

Temperature rise

The ph changes

29

What are the products in a metal hydroxide plus acid reaction

A salt and water

30

Are metal hydroxides soluble

Yes- they usually dissolve in water to form clear colour less solutions

31

Are metal oxides usually soluble

No but some of them such as sodium oxide can dissolve in water to form clear colourless solutions

32

What are the products of a metal oxide plus acid reaction

Salt and water

33

What can you observe during a metal oxide and acid reaction

Temperature rise and ph change

34

Are metal carbonates dissolve in water

No but sodium carbonate can (bicarbonate of soda) just remember that in both metal oxides and metal carbonates sodium is one of the only ones that dissolves

35

What are the products of a metal carbonate and acid reaction

A salt
Water
Carbon dioxide

36

What can you observe in an acid plus metal carbonate reaction

Bubbles being given off (co2)

A ph change

37

When hydrochloride acid reacts with a metal hydroxide carbonate etc is an ate or ide formed

It is always an Ide

38

When sulphuric acid reacts with an oxide hydroxide etcetera does it form an ate or an IDE

Always ate

39

What is electrolysis

Electrolysis is the process in which ionic substances are broken down into simpler substances using electricity. During electrolysis, metals and gases may form at the electrodes.

40

What is an ionic compound

The product of When a metal reacts with a non metal

41

What must the ions be to perform electrolysis

Free to move one does this by either dissolving the substance in water or melting it

42

How does electrolysis work

Positively charged ions move towards the negative electrode during electrolysis and receive electrons to turn them into their original form

Negatively charged ions move toward the positively charged electrode they lose electrons to form their original state and are oxidised

43

4 facts about the electrolysis of hydrochloric acid

Produces chlorine at the positive electrode
Produces hydrogen at the negative electrode

44

How to test for chlorine

Turns damp blue litmus paper red then white

45

The products of the electrolysis of water

Hydrogen at the negative electrode
Oxygen at the positive electrode

46

What percentage is the oxygen in the air

21%

47

What is reduction

The loss of oxygen from a substance many ores are oxides so one can extract metals through reduction

48

How do we extract very reactive metals compared to less reactive metals

The oxides of very reactive metals such as aluminium form stable oxides and other compounds
A lot of energy is needed to extract these this is often done through electrolysis

Less reactive materials such as iron can be split with their bonds fairly easily through reduction reactions using carbon

Unreactive metals like gold are extracted through various chemical reactions

49

What is rust a form of

Corrosion

50

What is rust

Hydrated iron (111) oxide

51

How to test that rust can not form with either water or air not present

For air but no water use calcium chloride so it reacts with any water in the test tube

For water but no air use boiled water with a layer of oil above it to stop air getting to it

52

What speeds up the formation of rust

Salt dissolved in water and acid

53

Why does aluminium not corrode

It is protected by a natural layer of aluminium oxide which stops the layer of pure aluminium coming into contact with air

Oxidisation on iron flakes off whereas oxidisation on aluminium does not

54

Use of metals:
Aluminium
Copper
Gold
Steal

Aluminium is low density and does not corrode so is suitable for bodies of planes

Copper is a good conducted of electricity and does not react with water so it is good for electrical wires and water pipes

Gold is a very good conducted and very unreactive so it is good for jewellery and electrical connections on circuit boards

Steel is cheap and strong so is suitable as a building material

55

How do alloys make a metal stronger

Alloys contain atoms of different sizes
Which distort the regular arrangement of atoms. This makes it harder for the layers to slide over each other so the metal is harder

56

What is brass and how is it used

It is an alloy of 70 percent copper and 30 percent zinc

57

What is 18 carat gold

75 percent gold and 25 percent copper
And other metals

58

What is duralumin

96 percent aluminium and 4 percent copper and other metals used in aircraft manufacture

59

Smart alloys

Smart alloys return to their original shape after being bent they are useful for spectacle frames and dental braces

60

What is an example of a smart alloy

Notinol returns to its original shape after being squealed by warming it
Notional tubes are used to open up arteries and as spectacle frames

61

What is nitinol made of

Nickel and titanium

62

What is an ore

A naturally occurring rock that contains metal or metal compounds at a sufficient amount to make it worthy to extract them

63

What is crude oil

A mixture of compounds called hydrocarbons

64

What is an alkane

A hydrocarbon with the formula
CnH2n plus 2
So an alkanes hydrogen is always double the amount of the carbon plus 2

65

What is meant by saturated hydrocarbon

The hydrogen is bonded to the carbon with double bonds making it relatively unreactive except for with oxigen

Alkanes are saturated

66

What are small hydrocarbons states

Gases

67

What are hydrocarbons with five to 12 carbons states

Liquids

68

Large hydrocarbons with many carbons are at which state

Solid

69

What is the sequence in events in distillation

Heating
Evaporating
Cooling
Condensing

70

What is complete combustion

The hydrogen in hydrocarbons oxidises to form water and the carbon oxidises to form carbon dioxide
Hydrocarbon+ oxygen=>water and carbon dioxide

71

What is incomplete combustion

Carbon monoxide produced, particles of carbon (seen as soot or smoke)

72

What happens to sulphur compounds in hydrocarbons when they are burnt

Soulful dioxide

73

What are the five gases that can be released into the air by the combustion of fuels

Water vapour
Carbon dioxide
Carbon monoxide
Particles ( carbon)
Sulphur dioxide

74

8 factors that have to be considered when deciding weather or not to use a fuel/ how to use a fuel

The energy value of the fuel in joules
The availability of the fuel
How the fuel can be stored
The cost of the fuel
The toxicity of the fuel
Any pollution that the fuel may cause such as sulcus dioxide
How easy it is to use the fuel

75

Positives of solid fuels (coal)
And negatives

Easier to store
Harder to light

76

Benefits of liquid and had fuels

Light easily
Flow through pipes

77

Problems with soulful dioxide

Causes acid rain when soulful dioxide dissolves in clouds

78

Effects of acid rain

Reacts with metals and rocks such as limestone buildings and statues are damaged as a result

Acid rain damages the waxy layer on leaves of trees and make it harder for plants to soak up the minerals they need for growth

Acid rain makes lakes and rivers too acidic for some aquatic life to survive

79

How is sulphur dioxide dealt with

It can be removed from waste gases after the combustion of the fuel by treating it with calcium carbonate to form calcium sulphate this can be used to make plaster board

80

What does a greenhouse gas do

Absorb thermal energy and prevent it from going back into space

81

The four steps of the greenhouse effect

The suns rays enter the earths atmosphere
Heat is reflected back off of the earths surface
Heat is absorbed by greenhouse gases such as co2 or methane
The earth gets hotter

82

Effect of global warming two things

Global weather patterns will change drought and flooding

Polar ice caps will melt raising sea levels increased coastal erosion and flooding of low lying land including land where major cities lay

83

How are scientists trying to control the amount of co2 in the atmosphere

Iron seeding of oceans

Converting carbon dioxide into hydrocarbons

84

Advantages of biofuels

Carbon neutral

85

Negatives about biofuels

Ethical issue that people think that it is bad to make fuel out of food crops

86

Problems with hydrogen fuel

Need electricity to produce which uses hydrocarbons to make

Not convenient, very flammable May explode must be compressed and chilled then stored in tough insulated tanks

87

What is the name for 1 2 3 and 4 carbons in a hydrocarbon

Meth
Eth
Prop
But

88

How is cracking done

Fractions containing large hydrocarbons are vaporised then passed over a hot catalyst to break them into smaller pieces

89

Why do we crack hydrocarbons

Large molecules aren't efficient
They don't flow easily
Crude oil often contains too many large hydrocarbons and too little small to meat demand

90

What is an Alkene

An unsaturated hydrocarbon this happens by the carbon atoms having double bonds
The formula for alkanes is to double the amount of carbons to get the hydrogens

91

Testing for alkenes

Bromine water is used
An Alkene will turn brown bromine water couler less as it reacts with the double bond

92

Use for alkenes

Polimers

93

What are Polimers

Very large molecules made when many smaller molecules join end to end the smaller molecules are called mine mets

94

Ethan can polomerise to form

Polyethene

95

Propane can polomerise to form

Poly proper

96

Use for poly ethane
Polypropene
Polychloerothene

Polyethene plastic bags and bottles

Polypropene crate and ropes

Polychlorothene water pipes and insulation

97

Uses of polymers

Ethane flexible cheap insulator plastic bags and bottles coating on wires

Proper flexible and strong buckets and crates

PVC tough cheap and long lasting window frames

Tetrafluoroethene tough and non stick
Coating on pans

98

Polymer problems

Are not biodegradable although chemicals can be added to make the degrade

When incinerated toxic gases are produced unless burning at very high temp

99

Problems with recycling

Difficult to seperate different plastics