Chemistry in society- Unit 3 Flashcards
1
Q
Haber process equation
A
N2 + H2 = NH3
2
Q
Ostwald process equation
A
NH3+H2O+O2=HNO3
3
Q
Catalyst used in haber process
A
Iron
4
Q
Catalyst used In Ostwald process
A
Platinum
5
Q
The haber process uses
A
Gases from the atmosphere
6
Q
Before you can do the Ostwald process what needs to happen first
A
The haber process
7
Q
What is fractional distillation
A
The seperation of crude oil into fractions according to their boiling points
8
Q
How many stages is there when manufacturing chemicals
A
4
9
Q
Stage 1 of manufacturing chemicals
A
Research and development
10
Q
Stage 2 of manufacturing chemicals
A
Laboratory process
11
Q
Stage 3 of manufacturing chemicals
A
Pilot plant
12
Q
Stage 4 of manufacturing chemicals
A
Production plant- final stage
13
Q
How many principles are in the design process
A
7
14
Q
Stage 1 of design process
A
Availablity Of feedstock
15
Q
Stage 2 of design process
A
Cost of the feedstock
16
Q
Stage 3 of design process
A
Sustainability of feedstock
17
Q
Stage 4 of design process
A
Opportunity’s for recycling
18
Q
Stage 5 of design process
A
Energy requirements
19
Q
Stage 6 of design process
A
Marketability of by-products
20
Q
Stage 7 of design process
A
Product yield( or atom economy)
21
Q
Full design process
A
Availablilty of feedstock Cost of the feedstock Sustainability of feedstock Opportunity’s for recycling Energy requirements Marketability of by-products Product yield
22
Q
Batch manufacturing
A
Advantages- suites for smaller scale production up to 100 tonnes per annum
- good for multistep reactions
Disadvantages- possibilities of contamination from one batch to the next
-filling and emptying takes time during which no Product is made = no money
23
Q
Continuous manufacturing
A
Advantages-suites to large scale production up to >1000 tonnes per annum
- suitable for fast single step processes
- more easily controlled via computers
Disadvantages-much higher capital cost before production can begin
- not versatile, can only make 1 product
- not cost effective when run below full capacity
24
Q
Capital costs
A
- Research and development
- plant construction
- Buildings
- infrastructures
25
Fixed costs
Depreciation of plants
Labour
Land purchase or rental
Sales experts
26
Variable costs
Raw material
Energy bills
Overheads
Efficient waste treatment
27
Factors influencing the process chosen
Availability And sustainably of feedstocks
Cost of feedstocks
Opportunity’s for recycling
28
How does the availability and sustainability of feedstocks influence the process chosen
Salt water is widely available and supplies are unlimited
29
How does the cost of feedstocks influence the process chosen
Salt water would have to be pumped to the plant
| Water may have to be filtered
30
How does opportunities for recycling influence the process chosen
I reacted sodium chloride solution would have to be separated from the sodium hydroxide and fed back to the plant
31
What is green chemistry
Green chemistry is the sustainable design of chemical products and chemical processes. It minimises the use of chemical substances that are hazardous to human health of the environment
32
Green chemistry principles
Better to prevent waste than to deal with it
Chemical processes should aim to incorporate all reactants in the final product
Chemical processes should aim to use and generate substances with minimal toxicity to human health and the environment
Modern chemists design reactions with the highest possible atom economy in order to minimise environmental impact.
Chemists achieve this by reducing raw materials and energy consumption
33
What is the goal of atom economy
In an ideal reaction all reactant atoms end up within the useful product molecule
No waste is produced
34
Inefficient, wasteful reactions have
Low atom economy
35
Efficient processes have
High atom economy and are important for sustainable development as they create less waste
36
A reaction may have
A high percentage yield but a low atom economy or vice versa
37
What is a limiting reactant
A limiting reactant is the substance that is fully used up and thereby limits the possible extent of the reaction. Other reactants are said to be in excess
38
Chemical reactions that take place in both directions are called
Reversible reactions
39
The position of the equilibrium does not
Depend on the starting position
40
What is a feedstock
A feedstock is a chemical from which other chemicals are manufactured. They are made from raw materials.
41
Examples of raw materials
```
Fossil fuels- coal, oil and natural gas
Metallic ores
Minerals- chlorine from sodium chloride
Water and air
Organic materials
```
42
Examples of products made from the batch process
Pharmaceuticals(medicines), dyes etc
43
Examples of products made from continuous process
Sulphuric acid, ammonia, iron, ethene
44
What are operating conditions
The conditions under which a chemical process operates to maximise economic efficiency
45
What are capital costs
Capital costs is when you are building the plant
46
What are fixed costs
These are costs that are the same wether 1 or 100tons of product are made
47
What is excess
Reactants are needed for a chemical reaction to take place. When one of the reactants is used up the reaction will stop. Any reactant which is left I reacted is said to be in excess
48
Equilibria(reversible reactions)
In a reversible reaction, if the conditions are not altered a balance point will be reached. At this point the reaction is said to be in equilibrium. At equilibrium the reactants change into products at exactly the same rate at which the products change back Into reactants.
49
At equilibrium the concentrations of the reactants and products
Remain constant but not necessarily equal
50
Changing concentration equilibrium
Increasing the concentration of reactants, or decreasing the concentration of the products shifts the position of the equilibrium to the right
Decreasing the concentration of reactants, or increasing the concentration of the products shifts the equilibrium to the left
51
Changing temperatures equilibrium
Increasing temperature favours the endothermic reaction
Decreasing the temperature favours the exothermic reaction
52
Catalyst equilibrium
A catalyst does not alter the position of equilibrium but does speed up the rate at which equilibrium is attained
53
Definition of enthalpy of combustion
The enthalpy of combustion is the energy released to the surroundings when one mole of a substance burns completely in oxygen
54
What can Hess’s law be used for
Hess’s law can be used to calculate enthalpy changes which are difficult or impossible to determine by experiment
55
Enthalpy of formation definition
The enthalpy of formation is the quantity of heat energy taken in or given out when 1 mole of a substance is formed from its elements in its natural state
56
What is a redox reaction
A redox reaction involves two half reactions- oxidation and reduction
These half reactions can be written as ion-electron equations
57
What is oxidation
Oxidation is loss of electrons
OIL
The ion-electron equation for oxidation must be written in reverse
58
What is reduction
Reduction is gain of electrons
| RIG
59
Oxidation and reduction are two half’s of
The same chemical reaction. The combined reaction is called a redox reaction
60
What is an oxidising agent
In a redox reaction the thing that is reduced is the oxidising agent- the thing that allows oxidation to occur
61
What is a reducing agent
In a redox reaction the thing that is oxidised is the reducing agent- the thing that allows reduction to occur
62
What is chromatography
Chromatography is a method of separating and analysing a mixture of soluble chemical substances
63
Uses of chromatography
Chromatography can be used to follow the course of a chemical reaction or to establish the products of a chemical reaction.
It can also be used to identify additives in food, analyse fibres found in crime scenes and fingerprints
64
What are the two stages in paper chromatography
Mobile and stationary phase
The solvent is the mobile phase and wet paper is the stationary phase
65
What is the retention factor
The retention factor can be used to compare the different components found in a sample.
If two substances have the same RF value it is likely that they are the same compound.
