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Chemistry Flashcards

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1
Q

What percentage is there of nitrogen in the air

A

78%

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2
Q

What percentage is there of argon in the air

A

0.9%

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3
Q

What percentage of co2 is there in the air

A

0.037%

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4
Q

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

A

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

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5
Q

How was the earths early atmosphere formed

A

Volcanic activity

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6
Q

What was the consistency of the earths early atmosphere

A

Mostly carbon dioxide

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7
Q

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

A

1 billion

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8
Q

What gases other than co2 probably existed in the early atmosphere

A

Water vapour, ammonia, methane

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9
Q

How did the oceans get formed

A

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

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10
Q

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

A

Mars and Venus as their atmospheres consist mainly of carbon dioxide

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11
Q

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

A

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

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12
Q

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

A

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

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13
Q

How is the level of the current atmospheres co2 increasing

A

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

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14
Q

How is the level of carbon dioxide maintained

A

Photosynthesis
Green plants all remove co2 from the air through photosynthesis

Combustion
Releases co2 into the air

Respiration
Releases co2 into the air

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15
Q

Steps of the carbon cycle

A

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

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16
Q

Ways humans are increasing the atmospheres co2 content

A

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

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17
Q

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

A

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

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18
Q

What is an example of conservation of mass

A

A precipitation reaction

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19
Q

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

A

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

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20
Q

What is copper sulphate

A

CuSO4

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21
Q

What is sodium hydroxide

A

NaOH

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22
Q

What colour precipitate does iron (II) produce

A

Green- turns brown when standing

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23
Q

What colour precipitate does iron (111)

Produce

A

Orangy brown

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24
Q

What colour precipitate does copper produce

A

Blue pale

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25
Q

What colour precipitate does zinc produce

A

White

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26
Q

4 features of acids

A

Have a low ph (1-6)

React with bases to form neutral compounds

Are corrosive when strong

Are irritant when weak

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27
Q

What is an indigestion remedy

A

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

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28
Q

What do you observe during a metal hydroxide and acid reaction

A

Temperature rise

The ph changes

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29
Q

What are the products in a metal hydroxide plus acid reaction

A

A salt and water

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30
Q

Are metal hydroxides soluble

A

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

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31
Q

Are metal oxides usually soluble

A

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

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32
Q

What are the products of a metal oxide plus acid reaction

A

Salt and water

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33
Q

What can you observe during a metal oxide and acid reaction

A

Temperature rise and ph change

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34
Q

Are metal carbonates dissolve in water

A

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

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35
Q

What are the products of a metal carbonate and acid reaction

A

A salt
Water
Carbon dioxide

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36
Q

What can you observe in an acid plus metal carbonate reaction

A

Bubbles being given off (co2)

A ph change

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37
Q

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

A

It is always an Ide

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38
Q

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

A

Always ate

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39
Q

What is electrolysis

A

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.

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40
Q

What is an ionic compound

A

The product of When a metal reacts with a non metal

41
Q

What must the ions be to perform electrolysis

A

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

42
Q

How does electrolysis work

A

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
Q

4 facts about the electrolysis of hydrochloric acid

A

Produces chlorine at the positive electrode

Produces hydrogen at the negative electrode

44
Q

How to test for chlorine

A

Turns damp blue litmus paper red then white

45
Q

The products of the electrolysis of water

A

Hydrogen at the negative electrode

Oxygen at the positive electrode

46
Q

What percentage is the oxygen in the air

A

21%

47
Q

What is reduction

A

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

48
Q

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

A

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
Q

What is rust a form of

A

Corrosion

50
Q

What is rust

A

Hydrated iron (111) oxide

51
Q

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

A

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
Q

What speeds up the formation of rust

A

Salt dissolved in water and acid

53
Q

Why does aluminium not corrode

A

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
Q 
Use of metals:
Aluminium 
Copper 
Gold 
Steal
A

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
Q

How do alloys make a metal stronger

A

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
Q

What is brass and how is it used

A

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

57
Q

What is 18 carat gold

A

75 percent gold and 25 percent copper

And other metals

58
Q

What is duralumin

A

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

59
Q

Smart alloys

A

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

60
Q

What is an example of a smart alloy

A

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
Q

What is nitinol made of

A

Nickel and titanium

62
Q

What is an ore

A

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

63
Q

What is crude oil

A

A mixture of compounds called hydrocarbons

64
Q

What is an alkane

A

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

65
Q

What is meant by saturated hydrocarbon

A

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

Alkanes are saturated

66
Q

What are small hydrocarbons states

A

Gases

67
Q

What are hydrocarbons with five to 12 carbons states

A

Liquids

68
Q

Large hydrocarbons with many carbons are at which state

A

Solid

69
Q

What is the sequence in events in distillation

A

Heating
Evaporating
Cooling
Condensing

70
Q

What is complete combustion

A

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

71
Q

What is incomplete combustion

A

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

72
Q

What happens to sulphur compounds in hydrocarbons when they are burnt

A

Soulful dioxide

73
Q

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

A 
Water vapour
Carbon dioxide 
Carbon monoxide 
Particles ( carbon) 
Sulphur dioxide
74
Q

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

A 
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
Q

Positives of solid fuels (coal)

And negatives

A

Easier to store

Harder to light

76
Q

Benefits of liquid and had fuels

A

Light easily

Flow through pipes

77
Q

Problems with soulful dioxide

A

Causes acid rain when soulful dioxide dissolves in clouds

78
Q

Effects of acid rain

A

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
Q

How is sulphur dioxide dealt with

A

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
Q

What does a greenhouse gas do

A

Absorb thermal energy and prevent it from going back into space

81
Q

The four steps of the greenhouse effect

A

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
Q

Effect of global warming two things

A

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
Q

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

A

Iron seeding of oceans

Converting carbon dioxide into hydrocarbons

84
Q

Advantages of biofuels

A

Carbon neutral

85
Q

Negatives about biofuels

A

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

86
Q

Problems with hydrogen fuel

A

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
Q

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

A

Meth
Eth
Prop
But

88
Q

How is cracking done

A

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

89
Q

Why do we crack hydrocarbons

A

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
Q

What is an Alkene

A

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
Q

Testing for alkenes

A

Bromine water is used

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

92
Q

Use for alkenes

A

Polimers

93
Q

What are Polimers

A

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

94
Q

Ethan can polomerise to form

A

Polyethene

95
Q

Propane can polomerise to form

A

Poly proper

96
Q

Use for poly ethane
Polypropene
Polychloerothene

A

Polyethene plastic bags and bottles

Polypropene crate and ropes

Polychlorothene water pipes and insulation

97
Q

Uses of polymers

A

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
Q

Polymer problems

A

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
Q

Problems with recycling

A

Difficult to seperate different plastics

Chem (9 decks)

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