paper 2 Flashcards
(86 cards)
1
Q
Collision theory
A
chemical reactions can only take place then the reacting particles collide with each other. The collisions must have sufficient energy
2
Q
rate of reaction
A
frequency of successful collisions
3
Q
what does inc conc mean on amount produced and ror
A
inc ror as more collisions, more product as there are originally more reactants
4
Q
hypothesis
A
proposal that could explain a fat or an observation- must be testable
5
Q
2 ways of required practical for ror. And give the problem for it
A
- Using a measuring cylinder, put 10cm^3 of sodium thiosulfate solution into a conical flask
- Place flask onto a printed black cross
- Add 10 cm^3 of HCl into the conical flask
- Swirl and start a stopwatch
- Look down through the top of the flask and after a certain time, the solution will go cloudy.
- Stop clocl when we can no longer see the cross
- Carry out the experiment again but with a lower conc of sodium thiosulfate solution
- Repeat the whole experiment and calculaate mean values for each conc of sodium thiosulfate solution. -don’t include any anomolous results
PROBLEM: different people have different eyesight= practical is not producible
Other way:
- Use measuring cyclinder to place 50 cm^3 of HCl in conical flask
- Attach conical flask to a bung and delivery tube
- Place delivery tube into a container filled with water.
- Place upturned measuring cylinder also filled with water over delivery tube
- Add 3cm strip of magnesium to HCl and start a stopwatch
- reaction produces hydrogen gas which is trapped in the measuring cylinder. - Every 10 seconds, measure the volume of hydrogen gas in the measuring cylinder and continue until no more is given off
- Repeat experiment using different conc of HCl
6
Q
What does it mean if a measurement is reproducible?
A
It can be repeated by another person or using a different technique or equipment and still get the same results
7
Q
If there is a smaller sized block, what does this mean?
A
It has a greater surface to volume ration than larger blocks
8
Q
Why is cotton wool used at the top of conical flasks in most practicals?
A
To allow the gas to escape but not the liquid
9
Q
activation energy
A
The minimum amount of energy that the particles must have in order to react (i.e. collide successfully)
10
Q
measure for mass and volume
A
Mass= grams Volume= cm^3
11
Q
measure for ror
A
g/s or cm^3/s
12
Q
why does increasing temp inc ror?
A
Because it increases the energy of the particles and because of this, they move faster which increases the frequency of collisions. Also means that more particles can overcome the activation energy barrier and collide successfully.
13
Q
Catalyst: what it is, why it is important and how it increases increases the rate of reaction
A
Increases the rate of chemical reactions but are note used up during the reaction. Different reactions need different catalysts.
- Important because they allow us to carry out reactions without needing to increase the temperature. This save money.
- Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy
14
Q
when is eq reached?
A
When the forwards and reverse reaction occurs at the same rate in a CLOSE system and a reversible reaction
15
Q
La Chatelier’s principle
A
If a system is at eq and a change is made to the condition, then the system will counteract the change
16
Q
what happens if the conc of the product decreases?
A
Then more reactant will react to form more of the product until eq is reached again
17
Q
What happens to eq when conc of reactant incs
A
More product will be formed until eq is reached again
18
Q
When happens to eq when there is an increase in temperature
A
EQ will shift with the endothermic side to decrease the temperature because it causes energy to be take in, causing the temperature to fall back to it’s original temp
19
Q
what happens to eq when there is a decrease in temp?
A
Eq will shift towards the exothermic die as it causes energy to be released there increasing temp back to normal
20
Q
what happens to eq when you increase pressure?
A
EQ shifts to the side with the smaller numer of molecules (talking about the big number beofre the equation.
21
Q
What happens to eq when pressure decreases
A
EQ shifts to the side with the highest number of molecules-
22
Q
What is a hydrocarbon
A
molecules made up of hydrogen and carbon atoms only
23
Q
Equation for methan
A
CH4
24
Q
Equation for Ethane
A
C2H6
25
Equation for propane
C3H8
26
Equation for Butane
C4H10
27
general formula for alkanes
CnH2n+2
28
why are alkanes saturated molecules?
Because the carbon atoms are fully bonded to hydrogen atoms by single bonds
29
Describe the flammability, viscosity and bp as you increase the size of the hydrocarbon
Flammability- as hydrocarbon molecules increase, the molecules get less flammable
Viscosity- as the size of the hydrocarbon molecules increases, the molecules et more viscous
BP- as you increase the size of the hydrocarbon, the boiling point incs
30
How do you release energy by using hydrocarbons
Combust them/ burn them
31
What happens during the combustion of hydrocarbobs
The hydrogen and carbons atoms in the fuel react with oxygen, The carbon and hydrogen are oxidised.
32
what is the formula for complete combustion and when does it happen
it happens when there is an unlimited/ not a lack of oxygen. Formula- CH4 + O2 ---> CO2 + H2O
33
When does incomplete combustion occur and give the two equations for it. And also explain the negative effects of the products of it
Occurs when there is a poor supply of O2. Formulas:
- CH4 + O2 --> CO + C + H2O
- CH4 + O2 --> C + H2O
C (soot): causes breathing problems and also reduces the amount of solar energy received= global dimming
CO (carbon monoxide): Toxic, absorbed in the lungs and binds with haemoglobin in red blood cells which means that there is a lower capacity in how much oxygen it can carry
34
Give all of the stages in fractional distillation
1. Crude oil is heated to a very high temperature= crude oil boils
2. Crude oil vapour is now fed into the fractional distillation column- column is hot at the bottom and cooler at the top
3. Hydrocarbons rise up the column- and condense when they reach their boiling point
4. Remaining hydrocarbons continue moving up the column
- add the extra details in the exam
35
what can fractional distillation help to produce
Help to produce fuels and feedstock for the petrochemical industry (feedstock= chemicals that is used to make other chemicals eg. Solvents, lubricants, polymers)
36
Give the conditions for catalytic cracking
High temperature and a catalyst
37
conditions for steam cracking
high temperature and steam
38
describe the bonds in alkenes
Double between two carbon atoms
39
Why are alkenes useful
- Used to make chemicals called polymers
| - Used as a starting material for other useful chemicals too
40
Compare the reactivity between alkanes and alkenes
alkenes are more reactive
41
give the test for alkenes
shake orange bromine water with an akene and if it is present, the bromine water turns colourless
42
What is a pure substance and explain what this means
A substance which is not mixed with any other substance
- Means that it melts and boils at a fixed temperature
- A pure substance is a single element or compound, not mixed with any other substance
43
formulation and what is carefully measured and why
Complex structure that has been designed as a useful product. The quantity of each component is carefully measured so that the product has the properties we need
44
What is a physical process
Does not involve chemical reactions and no new substance is made
45
What does paper chromatography allow us to do?
Allows us to separate substances based on their different solubilities
46
Solubility
Solubility is a measurement of how much of a substance will dissolve in a given volume of a liquid.
47
Solvent
Liquid that will dissolve substances
48
solute
Substance that is dissolved to make a solution
49
what is the stationary phase and the mobile phase in chromatography
Stationary- paper
| Mobile- solvent
50
Why does chromatography work and what affects how far a substance moves up the paper
Work because each chemical in the mixture will be attracted to the stationary phase to a different extent
- Chemicals strongly attracted to stationary phase will not move very far (vice versa)
- Also depends on the solubility of the water too
-
51
Why do you draw a pencil line for chroma
so the pen ink would not move up the paper with the solvent
52
Give all of the stages in chroma and give the key points of this practical
1. Use a rule to draw a horizontal pencil line on the chromatography paper- the line should be 2 cm from the bottom
2. Mark five pencil spots at equal distances across the line- leave at least 1 cm clear at each side
3. Use a capillary tube to put a small spot of each unknown and known food colours onto the pencil spots
4. Pour water into a beaker to a depth of 1cm
5. Attach the paper to a glass rod using tape and lower the paper into the beaker- The bottom of the paper should dip into the water .
6. Add lid to beaker to reduce evaporation of the solvent
7. The water will now move up the paper and the colours will be carried too. And during this time, it is careful that you do not move the beaker
8. REmove the paper when the water has travelled around 3/4 up the paper
9. Use a penicl line to mark the point where the water reached
10. Hang the paper up to dry
11. To identify the chemical of the colours, you find the Rf value which is- Distance moved by chemical/ distance moved by solvent
Key points:
- The pencil line with spots of ink must be above the surface of the water.
- The sides of the paper must not touch the side wall of the beaker because if it happens, it will interfere with the way that the water moves
53
atmosphere of the earth today
80% nitrogen
20% O2
Small amounts of other gases like CO2, H2O (vapour) and nobel gases.
54
What has happened to the atmosphere to cause it to change
1. - Volcanos releasing water vapour which condensed to form the oceans.
- Also produced nitrogen which gradually built up
- Released a lot of CO2 and small amounts of methane and ammonia
2. CO2 dissolved in the water to form a weak acid. This reacted in the sea to form precipitates (an insoluble solid formed by a reaction). Overtime, this formed sediments of carbonate rock on the sea bed.
3. Some CO2 in the sea was used to make corals and shells of organisms such as mussels. When these die, they formed sedimentary rock, limestone. Which decreased CO2
4. Around 2.7b years ago, photosynthetic algae first evolved in the oceans which produced O2. Over the following billion years, plants evolved which inced the amount of O2 in the atmosphere (allowing animals to evolve) and CO2
5. Fossil fuels
6. Humans
55
How is coal formed
1. Formed from the remains of ferns and trees
2. If these die in marshy wetlands then they do not decompose which can be due to a lack of O2 or acidic conditions which both prevent bacteria from carrying out decomposition
3. Over time (millions of years) , the plant remains are covered with sediment and are compressed. High temperature and pressure creates coal
56
How is crude oil formed
1. Formed from plankton which are tiny plants and animals found in the sea
2. When these die, they settle in mud on the sea-bed
3. If oxygen is not present, then they do not decompose.
4. And overtime (millions of years), they are compressed by sediment and heat and pressure then it converts into crude oil
57
where do you mainly find natural gases and how are they formed
Found near deposits of oil.
| - Natural gas is formed from plankton in a similar way to oil
58
What do we use recourses for?
Warmth, shelter, food and transport
59
What does finite mean
Cannot be replaced as quickly as they are being used
| - METAL AND FINITE ARE EXAMPLES OF THIS
60
sustainable
We can meet our needs without preventing future generations from meeting theirs
61
Give the stages in the green house effect
1. ENergy from the sun travels to earth as short wavelength radiation
2. Some of the short wavelength radiation simply deflects back in to space but most passes easily through the atmosphere
- Because short wl radiation does interact strongly with the gas molecules in the atmosphere
3. Energy from of the radiation is absorbed when it reaches the surface of the earth
4. The surface of the earth now radiates the energy as long wl radiation
5. Some of the long wl radiation interacts with the greenhouse gas molecules in the atmosphere- energy in long wl radiation is absorbed= inc temp
62
What will happen without the greehouse gas effect
Earth would be too cold for most living organisms to survive
63
how is methane release
- agriculture- growing rice in flooded paddy fields
| - Cows
64
what is one main problem to do with the complex system of global climate change- media
Simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased
65
Affects of climate change
1. Melting of polar ice sheets and glaciers- sea levels rise
| 2. Severe weather
66
importance of peer review
Helps to detect false claims or bias
67
Carbon footprint
Total amount of Co2 and other greenhouse gases are emitted over the full cycle of a product, service or event
68
How is sulfur dioxide produced hand what is bad about it
Some fossil fuels have sulfur impurities so when they are oxidised/ burnt, it produces sulfur dioxide.
- causes respiratory problems and acid rain which damages the waxy layer on the leave of tree making it more difficult for them to absorb the minerals they need to healthy growth. Also makes lakes too acidic for some aquatic life to survive.
69
How is nitrogen oxide produced
In the internal combustion in car engines and when the high temps make nitrgoen and oxygen react in the air causing it to be oxidised.
70
What is bad about carbon monoxide
Toxic gas. Colourless and odourless and so it not easily detected
71
Give an example where natural products have been replaced
Rubber from a sap of a tree has been replaced by synthetic rubber by using crude oil
72
What does potable water must have?
Sufficiently low levels of dissolved salts and can not have high levels of microbes eg bacteria
73
why is potable water not pure water?
Because it contains dissolved substances
74
Where does most of the drinking water come from in the UK?
rain water
75
how do you produce potable water from ground water
1. Filtered
| 2. Sterilised
76
Give the stages in getting potable water`
1. Choose a good source of fresh water eg river
2. Pass the water through filter beds. That is to remove materials such as leaves and suspended particles
3. Water is sterilised to kill microbes. In UK, we use chlorine but in other places they use ozone or ultraviolet light
77
How do you get potable water from sea or salty water and give the problem with them
```
Desalination
- Distillation
or
- Reverse osmosis
PROBLEM
Both require large amounts of energy= expensive
```
78
Give the stages in the treatment of waste water and what does the treatment of agrictulatural waste and sewage water require first? and the same with industrial waste
1. Screening and grit removal
2. Sedimentation to produce sewage sludge and effluent
3. Anaerobic digestion of sewage sludge
4. Aerobic biologic treatment of effluent
SEWAGE AND AGRICULTURAL WASTER REQUIRE REMOVAL OF ORGANIC MATTER AND HARMFUL MICROBES FIRST.
Industrial waste water may require removal of organic matter and harmful chemicals
79
Why do you need to extract things from low grade ores
Because substances may be scarce
80
Stage in Phyto mining
1. Plants are grown on land containing the metal compound they want
2. These plants absorb the metal compound and they concentrate it in their tissue
3. Plants are then harvested and burned
4. At the end, the ash contains a relatively high conc of the metal compound.
5. Now you need to extract the metal from the compound- in copper compounds, we can displace copper using iron. Iron is more reactive than copper. we usually use scrap iron= cheap
- Or we can use electrolysis
81
Stages in bioleaching
1. Bacteria are mixed with the low grade ore
2. Bacteria carries out chemical reactions and they produce a solution called a leachate- contains the metal compound we want
3. Now you need to extract the metal from the compound- in copper compounds, we can displace copper using iron. Iron is more reactive than copper. we usually use scrap iron= cheap
- Or we can use electrolysis
82
Give two positives of using bioleaching and Phyto mining
1. Allows us to economically extract metals from low-grade ores
- important as Earth's recourses of metal are limited
2. Both methods do not involve digging, transporting and disposing of large amounts of rock like normal mining
83
what does the Life cycle assessment attempt to do?
Put a number on the environmental impact of a product
84
Give the stages carried out in LCAs to assess their impact on the environment
1. Extracting and processing raw materials
2. Manufacturing and packaging
3. use and operation during it's life time
4. Disposal at the end of it's useful life
5. Transport and distribution
IT FOR PLASTIC BAG AND PAPER
1. Crude oil needed for plastic= non-renewable
Paper= trees= renewable
- both need to be chemically processed= energy= release of waste products
2. Plastic bags strong= long life
Paper bags weak= short life
5. Paper bags= heavier= more energy to transport
6. Plastic in non biodegradable= litter
85
Give the 2 problems with LCA
1. You cannot always be certain of how damaging these are to the environment
2. Life cycles can be biased eg to support claims by advertisers
86
explain the term cracking
a form of thermal decomposition breaking large alkanes into smaller more useful alkanes and alkenes
