C7 Flashcards
(127 cards)
0
Q
The government puts strict controls on everything to do with chemical processes to protect what?
A
To protect workers, the general public and the environment.
1
Q
Bulk chemicals are?
A
Chemicals that are produced on a large scale.
2
Q
Give three regulations that the government controls of chemical processes.
A
1) Using chemicals- they restrict how much can be used and require signs to warn public.
2) Storage- poisonous chemicals must be stored in either sealed containers or well- ventilated store cupboards.
3) Transport- lorries transporting chemicals must display hazard symbols and identification numbers.
3
Q
Give the five different stages involved in producing chemicals.
A
1) Preparation of feedstock
2) Synthesis
3) Separation of products.
4) Monitoring the purity if product
5) Handling of by-products and wastes.
4
Q
First step of chemical synthesis: why are raw materials converted into feedstocks?
A
Raw materials are naturally occurring substances which are needed.
Feedstocks are the actual reactants needed for the process.
The raw materials are purified or changed some way to make feedstocks.
5
Q
The second stage of producing chemicals: synthesis.
A
Feedstocks are turned into products. The conditions are carefully controlled to make sure the reaction happens and at a good rate.
6
Q
Step 3 of producing chemicals: the products are separated
A
Once the chemical reaction is done, you will get the substance you want and other chemicals you don’t want and leftover reactants.
Everything has to be separated out so it can be dealt with in different ways.
7
Q
4th step in producing chemicals: purity of product monitored
A
Different industries need different levels of purity depending on what the product will be used for.
If a slightly impure product will do the job it is meant for, there’s no point wasting money on purification.
8
Q
5th step of producing chemicals: by products are dealt with
A
By-products are used in another reaction or sold.
Waste heat can be used for other reactions to save energy and money.
Waste products are carefully disposed of and regulated by the government so they do not harm people or environment.
9
Q
A + B ——-> AB =
A
= exothermic
10
Q
AB ———> A + B =
A
= Endothermic
11
Q
What type of reaction is one when the energy released by forming bonds is greater than the energy needed to break them?
A
Exothermic
12
Q
What type of reaction is one that when the energy used to break bonds is greater than the energy than the energy released by forming them?
A
Endothermic
13
Q
Activation energy=
A
= the minimum amount of energy needed for bonds to break and a reaction to start.
14
Q
What happens if the energy input is less than the activation energy?
A
Nothing will happen.
15
Q
How do catalysts lower the activation energy?
A
Catalyst lower the activation energy needed for reactions to happen by providing alternative routes.
16
Q
What’s a catalyst?
A
A substance which changes the speed of the reaction, with ought being used up itself.
17
Q
What is reversible reaction?
A
One where the products of the reaction can themselves react to produce the original reactants.
A + B —–> C + D
<——
18
Q
What happens when an equilibrium is obtained?
A
The relative (%) quantities of reactants and products will reach a certain balance and stay there.
19
Q
What is a dynamic equilibrium?
A
The reaction is taking place in both directions, but the overall effect is nil because the forward and reverse reactions cancel each other out.
20
Q
N2 + 3H2 —–>
A
2NH3
21
Q
What are the industrial conditions for the Haber process?
A
Pressure:200 atmospheres
Temperature: 450 degrees
Catalyst: Iron
22
Q
Where his nitrogen and hydrogen found for the Haber process
A
Nitrogen is easily found as it takes up 78% of the atmosphere.
Hydrogen comes from the cracking of chemicals in natural gas using steam.
23
Q
Describe why the industrial conditions for the Haber process are set how they are.
A
Pressure: higher pressures favour the forward reaction, so the pressure is set as high as possible to give best % yield without making the plant to expensive to build.
Temperature: Higher temperatures favour the endothermic reaction, so lower temperatures work better. However, low temperatures will give a slow rate of reaction so they increase the temperature anyway.
Iron: Is a catalyst, helps speed up reaction.
24
What is nitrogen fixation?
Is the process of turning N2 from the air into useful nitrogen compounds like ammonia.
25
Why do chemists want to be able to mimic enzymes such as nitrogen- fixing bacteria?
So that processes like the Haber process can be carried out at room temperature.
26
Is nitrogen fixation a sustainable process?
1) will the raw materials run out?
2) how good is the atom economy?
3) what do I do with my waste products?
4) what are the energy costs?
5) will it damage the environment?
6) what are the earth and safety risks?
7) are there any benefits and risks to society?
8) Is it profitable?
1) hydrogen comes from fossil fuels which are non- renewable
Nitrogen comes form the air and will most likely not run out.
2) there is no waste in the reaction, so the atom economy is good.
3) there are no waste products because they are recycled.
4) lots of energy us needed to keep the reaction at high temperatures and pressures.
5) fertilisers made from nitrogen and hydrogen cause eutrophication.
6) working at high temps and atmospheres can be dangerous
7) making ammonia helps food production
8) yes, ammonia making is a big business.
27
What are alkanes made of?and are they saturated or unsaturated?
Alkanes are made up of chains of carbon atoms surrounded by hydrogen atoms.
The only contain single covalent bonds between carbon atoms so they are saturated.
28
What is the formula for all alkanes?
Cn + H2n + 2
29
Give the molecular formula for methane,ethane,propane and butane.
Methane: CH4
Ethane: C2H6
Propane: C3H8
Butane: C4H10
30
Alkanes burn to produce what?
To produce carbon dioxide and water
Alkane+ oxygen--> carbon dioxide+ water
31
What do alkanes not react with?and why?
They do not react with aqueous reagents( substances dissolved in water).
Alkanes don't react because the C-C bonds and C-H bonds are difficult to break.
32
What is the general formula for an alcohol?
CnH2n+1OH
33
Name the two first alcohols and their chemical formula.
Methanol - CH3OH
Ethanol - C2H5OH
34
Compare alcohols with alkanes and water in terms of their physical properties.
1) Ethanol is soluble in water. Alkanes are insoluble
2) Ethanol and water are both good solvents.
3) boiling point of ethanol is 78 C . Boiling pint of water is 100 C
4) Ethanol is a liquid at room temperature, it's also volatile. Methane and ethane are also volatile, but are gases at room temperature.
35
Name several uses for alcohols and why are they so useful?
They can dissolve a lot of compounds that water can't like hydrocarbons and oils.
Used to make perfumes, methylated spirit, paint cleaner, fuel for cars.
36
What is fermentation?
Fermentation uses yeast to convert sugars into ethanol. Carbon dioxide is also produced.
Yeast
Sugar------------> ethanol carbon dioxide
37
Describe the zymase contained in yeast cells.
Yeast cells contain zymase, an enzyme that acts as a catalyst in fermentation.
Fermentation works best at 39 degrees because zymase works best at this temperature.
If it gets to hot the zymase becomes denatured.
Zymase works best at an PH of 4.
38
Why is it important to prevent oxygen getting into the fermentation process?
Because oxygen converts the ethanol to ethanoic acid, which lowers the PH and can stop the enzyme working.
When the concentration reaches about 10 to 20%, the fermentation reaction stops, because the yeast gets killed by the ethanol.
39
Explain how ethanol solution can be concentrated by distillation.
1) the ethanol solution is put in a flask below a fractioning column.
2) the solution is heated so the ethanol boils.The ethanol vapour travels up the column, cooling down as it goes.
3) the temperature is such that anything with a higher boiling point than ethanol( like water) cools to a liquid and flows back to the solution at the bottom.
4) this means that only pure ethanol vapour reaches the top of the column.
5) the ethanol flows through a condenser- where it is cooled to a liquid which is then collected.
40
Explain how ethanol can be made from biomass.
Waste biomass is the parts of plants that are normally throw away.
Waste biomass cannot be fermented in the normal way because it contains a lot of cellulose( yeast can only convert sugars).
E.coli bacteria can be genetically modified so they can convert cellulose in to waste biomass into ethanol.
The optimum conditions for this process are a temperature of 35 C and pH 6.
41
How similar is the sustainability of the biomass method to the standard fermentation method?
Very similar because they both use similar processes.
The advantage of using biomass is that you don't have to grow crops specially for producing ethanol- you can use the waste from other crops.
42
Explain how ethane can be reacted to make Ethanol.
Fermentation is to slow for making ethanol on a large scale.
Ethane is one of the hydrocarbons found in crude oil and natural gas.
It is 'cracked' to form ethane and hydrogen gas.
Ethene will react with steam (H2O) to make ethanol.
The temperature needed for the reaction is 300Celsius and a pressure of 70 atmospheres.
Phosphoric acid is used as a catalyst.
43
What is carboxylic acids function group?
'COOH'
44
Carboxylic acids react with metals to give what?
To give a salt and hydrogen.
45
Carboxylic acids react with carbonates to give what?
A salt, water and carbon dioxide.
46
Carboxylic acids react with alkalis to form what?
A salt and water.
47
Why does wine and beer taste rancid when left in the air?
The ethanol reacts with the oxygen to produce ethanoic acid which gives the strong smell and taste.
48
What is the functional group of Esters?
-COO-
49
Give all the uses for Esters.
Many esters have pleasant smells- often sweet and fruity.
They are also quite volatile , makes the ideal for perfumes.
Some esters are used as solvents for paint, in, and glue.
Esters are also used as plasticisers- they are added to plastics to make them more flexible.
50
Fatty acids are?
Carboxylic acids with long chains.
51
What is Glycerol?
An alcohol.
52
Fatty acids and glycerol combine to make what?
Fats and oils.
53
What does most of a fat or oil consist of?
They consist of fatty acid chains.
54
Why do organisms store fats?
Fats have a lot of energy packed into them, so they are good at storing energy.
When an organism has more energy than it needs it stores the extra as fat,so it can use it when it needs more energy.
55
Describe animal fats.
Animal fats have mainly saturated hydrocarbon chains. They contain very few C=C bonds. They are normally solid at room temperature.
56
Describe vegetable oils.
They have mainly saturated hydrocarbon chains. They contain lots of C=C. They are normally liquid at room temperature.
57
Name all the stages involved in making an Ester.
1) Refluxing - reacting
2) Distillation
3) Purification
4) Drying
58
In the stages involved in making an Ester, describe Refluxing.
To make Ethyl ethanoate you need to react ethanol with ethanoic acid, using a catalyst such as concentrated sulfuric acid to speed things up.
The mixture is gently heated in a flask fitted with a condenser- This
Catches the vapours and recycles them back into the flask, giving them time to react- this is called Refluxing.
59
In the stages involved in making an Ester, explain distillation.
The mixture is heated below a fractioning column. As it starts to boil, the vapour goes up the fractioning column.
When the temperature at the top of the column reaches the boiling point of ethyl ethanoate, the liquid that flows out of the condenser is collected. This liquid is impure ethyl ethanoate.
60
In the stages involved in making an Ester, describe the purification.
The mixture is shaken with sodium carbonate solution to remove impurities. Ethyl ethanoate doesn't mix with the water in the sodium carbonate solution, so the mixture separates into two layers, and the lower layer is tapped off.
The remaining upper layer is then shaken with concentrated calcium chloride solution to remove ethanol, again the lower layer can be tapped off and removed.
61
In the several stages of making Ester, explain the method of drying.
Any remaining water in the ethyl ethanoate can be removed by shaking it with lumps of anhydrous calcium chloride,which absorb water- this is called drying. Finally, the Ester is separated from the anhydrous calcium chloride through filtration.
62
What does qualitative tell you about a sample?
Tells you which substances are present in a sample.
| It doesn't tell you how much of each substance there is.
63
What does Quantitative analysis tell you about a substance?
Tells you how much of a substance is present in a sample.
It can be used to work out the molecular formula of a sample.
For example, if you had a sample containing carbon and hydrogen you'd know it's a hydrocarbon, but without quantitative analysis, you won't know if it's methane, butane etc.
64
Why do people only analyse just a sample of a material under test?
1) it might be difficult to test all of the material.
2) Taking a sample also means that if something goes wrong with the test, you can go back for another sample and try again.
3) a sample must represent the bulk material, it would not tell you anything useful if it didn't.
65
What does a standard procedures mean?
Means everyone does things the same way.
66
Wy are there standard procedures?
Standard procedures are chosen because they're the safest,most effective and most accurate methods to use.
They are useful because whenever a test is done, the result should always be the same- it should give reliable results.
67
What is chromatography?
Is an analytical method used to separate the substances in a mixture.
68
What are the two phases of chromatography?
A mobile Phase- Where the molecules can move. This is always a liquid or a gas.
A stationary phase- where the molecules can't move. This can be a solid or a really thick liquid.
69
Concentration=
Mass of solute/ volume of solution
70
100cm cubed =
= 0.1 decimetre cubed
71
N2 + 3H2 ----->
2NH3
72
What are the industrial conditions for the Haber process?
Pressure:200 atmospheres
Temperature: 450 degrees
Catalyst: Iron
73
Where his nitrogen and hydrogen found for the Haber process
Nitrogen is easily found as it takes up 78% of the atmosphere.
Hydrogen comes from the cracking of chemicals in natural gas using steam.
74
Describe why the industrial conditions for the Haber process are set how they are.
Pressure: higher pressures favour the forward reaction, so the pressure is set as high as possible to give best % yield without making the plant to expensive to build.
Temperature: Higher temperatures favour the endothermic reaction, so lower temperatures work better. However, low temperatures will give a slow rate of reaction so they increase the temperature anyway.
Iron: Is a catalyst, helps speed up reaction.
75
What is nitrogen fixation?
Is the process of turning N2 from the air into useful nitrogen compounds like ammonia.
76
Why do chemists want to be able to mimic enzymes such as nitrogen- fixing bacteria?
So that processes like the Haber process can be carried out at room temperature.
77
Is nitrogen fixation a sustainable process?
1) will the raw materials run out?
2) how good is the atom economy?
3) what do I do with my waste products?
4) what are the energy costs?
5) will it damage the environment?
6) what are the earth and safety risks?
7) are there any benefits and risks to society?
8) Is it profitable?
1) hydrogen comes from fossil fuels which are non- renewable
Nitrogen comes form the air and will most likely not run out.
2) there is no waste in the reaction, so the atom economy is good.
3) there are no waste products because they are recycled.
4) lots of energy us needed to keep the reaction at high temperatures and pressures.
5) fertilisers made from nitrogen and hydrogen cause eutrophication.
6) working at high temps and atmospheres can be dangerous
7) making ammonia helps food production
8) yes, ammonia making is a big business.
78
What are alkanes made of?and are they saturated or unsaturated?
Alkanes are made up of chains of carbon atoms surrounded by hydrogen atoms.
The only contain single covalent bonds between carbon atoms so they are saturated.
79
What is the formula for all alkanes?
Cn + H2n + 2
80
Give the molecular formula for methane,ethane,propane and butane.
Methane: CH4
Ethane: C2H6
Propane: C3H8
Butane: C4H10
81
Alkanes burn to produce what?
To produce carbon dioxide and water
Alkane+ oxygen--> carbon dioxide+ water
82
What do alkanes not react with?and why?
They do not react with aqueous reagents( substances dissolved in water).
Alkanes don't react because the C-C bonds and C-H bonds are difficult to break.
83
What is the general formula for an alcohol?
CnH2n+1OH
84
Name the two first alcohols and their chemical formula.
Methanol - CH3OH
Ethanol - C2H5OH
85
Compare alcohols with alkanes and water in terms of their physical properties.
1) Ethanol is soluble in water. Alkanes are insoluble
2) Ethanol and water are both good solvents.
3) boiling point of ethanol is 78 C . Boiling pint of water is 100 C
4) Ethanol is a liquid at room temperature, it's also volatile. Methane and ethane are also volatile, but are gases at room temperature.
86
Name several uses for alcohols and why are they so useful?
They can dissolve a lot of compounds that water can't like hydrocarbons and oils.
Used to make perfumes, methylated spirit, paint cleaner, fuel for cars.
87
What is fermentation?
Fermentation uses yeast to convert sugars into ethanol. Carbon dioxide is also produced.
Yeast
Sugar------------> ethanol carbon dioxide
88
Describe the zymase contained in yeast cells.
Yeast cells contain zymase, an enzyme that acts as a catalyst in fermentation.
Fermentation works best at 39 degrees because zymase works best at this temperature.
If it gets to hot the zymase becomes denatured.
Zymase works best at an PH of 4.
89
Why is it important to prevent oxygen getting into the fermentation process?
Because oxygen converts the ethanol to ethanoic acid, which lowers the PH and can stop the enzyme working.
When the concentration reaches about 10 to 20%, the fermentation reaction stops, because the yeast gets killed by the ethanol.
90
Explain how ethanol solution can be concentrated by distillation.
1) the ethanol solution is put in a flask below a fractioning column.
2) the solution is heated so the ethanol boils.The ethanol vapour travels up the column, cooling down as it goes.
3) the temperature is such that anything with a higher boiling point than ethanol( like water) cools to a liquid and flows back to the solution at the bottom.
4) this means that only pure ethanol vapour reaches the top of the column.
5) the ethanol flows through a condenser- where it is cooled to a liquid which is then collected.
91
Explain how ethanol can be made from biomass.
Waste biomass is the parts of plants that are normally throw away.
Waste biomass cannot be fermented in the normal way because it contains a lot of cellulose( yeast can only convert sugars).
E.coli bacteria can be genetically modified so they can convert cellulose in to waste biomass into ethanol.
The optimum conditions for this process are a temperature of 35 C and pH 6.
92
How similar is the sustainability of the biomass method to the standard fermentation method?
Very similar because they both use similar processes.
The advantage of using biomass is that you don't have to grow crops specially for producing ethanol- you can use the waste from other crops.
93
Explain how ethane can be reacted to make Ethanol.
Fermentation is to slow for making ethanol on a large scale.
Ethane is one of the hydrocarbons found in crude oil and natural gas.
It is 'cracked' to form ethane and hydrogen gas.
Ethene will react with steam (H2O) to make ethanol.
The temperature needed for the reaction is 300Celsius and a pressure of 70 atmospheres.
Phosphoric acid is used as a catalyst.
94
What is carboxylic acids function group?
'COOH'
95
Carboxylic acids react with metals to give what?
To give a salt and hydrogen.
96
Carboxylic acids react with carbonates to give what?
A salt, water and carbon dioxide.
97
Carboxylic acids react with alkalis to form what?
A salt and water.
98
Why does wine and beer taste rancid when left in the air?
The ethanol reacts with the oxygen to produce ethanoic acid which gives the strong smell and taste.
99
What is the functional group of Esters?
-COO-
100
Give all the uses for Esters.
Many esters have pleasant smells- often sweet and fruity.
They are also quite volatile , makes the ideal for perfumes.
Some esters are used as solvents for paint, in, and glue.
Esters are also used as plasticisers- they are added to plastics to make them more flexible.
101
Fatty acids are?
Carboxylic acids with long chains.
102
What is Glycerol?
An alcohol.
103
Fatty acids and glycerol combine to make what?
Fats and oils.
104
What does most of a fat or oil consist of?
They consist of fatty acid chains.
105
Why do organisms store fats?
Fats have a lot of energy packed into them, so they are good at storing energy.
When an organism has more energy than it needs it stores the extra as fat,so it can use it when it needs more energy.
106
Describe animal fats.
Animal fats have mainly saturated hydrocarbon chains. They contain very few C=C bonds. They are normally solid at room temperature.
107
Describe vegetable oils.
They have mainly saturated hydrocarbon chains. They contain lots of C=C. They are normally liquid at room temperature.
108
Name all the stages involved in making an Ester.
1) Refluxing - reacting
2) Distillation
3) Purification
4) Drying
109
In the stages involved in making an Ester, describe Refluxing.
To make Ethyl ethanoate you need to react ethanol with ethanoic acid, using a catalyst such as concentrated sulfuric acid to speed things up.
The mixture is gently heated in a flask fitted with a condenser- This
Catches the vapours and recycles them back into the flask, giving them time to react- this is called Refluxing.
110
In the stages involved in making an Ester, explain distillation.
The mixture is heated below a fractioning column. As it starts to boil, the vapour goes up the fractioning column.
When the temperature at the top of the column reaches the boiling point of ethyl ethanoate, the liquid that flows out of the condenser is collected. This liquid is impure ethyl ethanoate.
111
In the stages involved in making an Ester, describe the purification.
The mixture is shaken with sodium carbonate solution to remove impurities. Ethyl ethanoate doesn't mix with the water in the sodium carbonate solution, so the mixture separates into two layers, and the lower layer is tapped off.
The remaining upper layer is then shaken with concentrated calcium chloride solution to remove ethanol, again the lower layer can be tapped off and removed.
112
In the several stages of making Ester, explain the method of drying.
Any remaining water in the ethyl ethanoate can be removed by shaking it with lumps of anhydrous calcium chloride,which absorb water- this is called drying. Finally, the Ester is separated from the anhydrous calcium chloride through filtration.
113
What does qualitative tell you about a sample?
Tells you which substances are present in a sample.
| It doesn't tell you how much of each substance there is.
114
What does Quantitative analysis tell you about a substance?
Tells you how much of a substance is present in a sample.
It can be used to work out the molecular formula of a sample.
For example, if you had a sample containing carbon and hydrogen you'd know it's a hydrocarbon, but without quantitative analysis, you won't know if it's methane, butane etc.
115
Why do people only analyse just a sample of a material under test?
1) it might be difficult to test all of the material.
2) Taking a sample also means that if something goes wrong with the test, you can go back for another sample and try again.
3) a sample must represent the bulk material, it would not tell you anything useful if it didn't.
116
What does a standard procedures mean?
Means everyone does things the same way.
117
Wy are there standard procedures?
Standard procedures are chosen because they're the safest,most effective and most accurate methods to use.
They are useful because whenever a test is done, the result should always be the same- it should give reliable results.
118
What is chromatography?
Is an analytical method used to separate the substances in a mixture.
119
What are the two phases of chromatography?
A mobile Phase- Where the molecules can move. This is always a liquid or a gas.
A stationary phase- where the molecules can't move. This can be a solid or a really thick liquid.
120
Concentration=
Mass of solute/ volume of solution
121
100cm cubed =
= 0.1 decimetre cubed
122
What is chromatography?
Chromatography is an analytical method which is used to seperate a mixture into the substances it is made out of. Chromatography has two phases: the mobile phase where molecules can move (liquid or gas) and a stationary phase where the molecules can't move (solid or thick liquid).
123
What does the distance travelled by chemicals during chromatography tell you?
1) how soluble the chemical is in the solvent
| 2) how attracted the chemical is to the paper
124
What is thin layer chromatography (tlc)?
Chromatography where the stationary phase is a thin layer of solid (silica gel spread onto a glass plate). The mobile phase is a solvent such as ethanol.
125
What is the result of chromatography analysis?
A chromatogram.
126
How can you calculate Rf value on a chromatogram? And what are the uses?
Some spots on a chromatogram may be colourless. If they are you need to use a locating agent to show where they are e.g. you might need to spray the chromatogram with a reagent.
Rf = distance travelled by solute/ distance travelled by solvent
Chromatography is often used to see if a certain substance is present in a mixture. You run a pure, known sample of the substance alongside the unknown mixture. If the Rf values match, the substances maybe be the same but it doesn't definitely mean they are the same.
Chemists use standard reference materials (SRMs) to check the identities of substances. These have carefully controlled concentrations and purities.
