C7 Flashcards
What are the basic raw materials of the chemical industry?
- crude oil, air water, vegatable materials, rocks and minerals such as metal ores, salt, limestone and gypsum
What is the first step in any chemical process?
- converting raw materials into purified feedstocks
What is a general process for any chemical process?
- use enrgy or water to prepare raw materials to become feedstocks
- complete a chemical reaction using a catalyst
- possibly uses the energy produced by the reaction
- recycle any unchanged reactions and repeat the process
5 seperate and purify products from by products and waste
What are the products of the chemical industry?
- Basic organic: chlorine,sodium,hydroxide,sulfuric acid, fertilisers- bulk chemicals
- Petrochemicals and polymers
- fuels and products like polymers
- dyes , paints and pigments - Pharmaceuticals
- drugs, medicines - Specialty chemicals
- food flavourings, liquid crystal chemicals in falt screen displays
How has the chemcial industry tried to make a ne feedstock?
- DuPont- ferments renewable plant material
- makes polymers(Sorona) by converting the fermented plant material into fibres- for clothing
- plant material fermented with bacteruia= malonic acid
- Negatives: biomass issues
- land
- needs fertilisers
- needs energy to transport and harvest material
How do you calculate percentage yield?
percentage yield=actual yield divided by theoretical yield
e.g. Calcium carbonate = calcium oxide + carbon dioxide
calcium carbonate= 40+12+(16 times 3)= 100
calcium oxide = 40 +16= 56
theoretical yield= 56g.
actual yield = 48g.
48 divided by 56 times 100 = 85.7%
What is the equation for atom economy?
atom economy= mass of atoms in product divided by mass of atoms in the reactants
times 100
eg.calcium oxide=- 56
calcium carbonate =100
56 divided by 100 times 100 = 56%
What is an example pf the chemical industry implenting one of its aims?
- remove toxic health hazards
- replace toxic chemicals with non- toxic ones
- Monsanto used hydrogen cyanide in weedkiller
- hydrogen cyanide- removed from the process
How is energy generally used in the manufacturing of chemical products?
- to raise the temperature of the reactants so a reaction begins or continues
- to haet a mixture of liquids to seperatew and purify products by distillation
- to dry productsts
- to process waste
How is the industry trying to become more efficient?
- prevent loses of steam in leaking valves or stem pipes by installin insulation
- using the energy from exothermic reactions to generate electric power to contribute to the income of the process
- using catalyst eg. enzymes
- lower the temperature of some reaction
- less energy
- limit being denatured
How is waste reduced in the chemical industry?
- high atom enconomy
- increased recycling
- find uses for by- products
What is closed loop recycling?
- waste material is collected and used to manufacture the same product
What is open loop recycling?
this is where waste is collected and used to manufacture another yet lower quality product
How is harmful waste dealt with by the chemical industry?
- filtered, distilled, centrifuged
- netralised with acids and alkalis
- broken down with microorganisms
What are alkanes and what are their properties?
- fuel- gas - petrol
- Phsical properties
- insoluble in water
- 4carbon= gas
- 4-17 carbons=liquid
17 or more = solid
Chemical
- burn, falmmable
- strong covalent bonds
- do not react with acids or alkalis
What are alkenes?
What is a sturated and unsaturated hydro carbon?
- Alkane- not very reactive
- saturated
Alkenes- unsaturated
- double carbo bind
- increases reactivity of a molecule as it can add more hydrogen than alkanes
eg. plastic and polymers made from ethene
What are alcohols used for ?
- drink- beer , wine
- as asolvent
- used in cosmetic lotion+perfumes
- feddstocks
- adhesives, foams and wind screen fluid
Wgat is the structure and physical properties of alcohols?
- liquid at room temperature
- boiling point is less than water
What are the chemical properties of alcohols?
- highly flammable
- fuels
- reacts with sodium similary to water as
- oH
- in reactions only the hydrogen in the oh reacts while the other hydrogens are unreactive
What are the three ways ethanol acn be produced?
- fermentation
- biotechnology
- chemical synthesis
How is ethanol made from plants?
- some parts of the plant fermented
- Cellulose polymers extracted and heated with acid to break it down into glucose
– glucose= ethanol + carbon dioxide
- lower concentration
of ethanol 14 to 15 %
- can be distilled to increase concentration to 40-50%
Which stages require energy during the production odf ethanol?
- producing fertilisers for plants to grow
- transporting the feedstocks to the factory
- processing the feedstocks
- transporting the ethanol to its point of use
What are the three different energy balances from the feedstocks used to make ethanol?
-sugar cane 8.3-10.2 sugar cane can only br grown in tropical and subtropical climates used in Brazil
sugar beet 1.4- 2.1 used in UK
coen 1.3-1.6 used in US
How can ethanol be produced with biotecnology?
- modifying bacteria so they can breakdown a wide range of sugar
sugar= ethanol + carbon dioxde
- optimun temp. 25-37 and 6-7 pH
How can ethanol be produced using chemical synthesis?
- feedstocks ethene -produced by creating ethane from natral gas
- not renewable
- at 300 celcius 60 to 70 times atmospheric pressure
ethene +steam= ethanol
- atom economy =100%
– yet a side reaction produces polyethene
- yield 95%
How is the ethanol purified from chemical synthesis?
- 96% ethanol 4% water
placed on zeotites- special; compound with tiny holes in it
- water molecules go through ethanol left behind
What is the structure and names of organic acids?
-carboxylic acids
How is vinegar made?
ehtanol is oxidised to produce ethanoic acid or vinegar
What is the difference between strong and weak acids?
pH1-strong acids- nitric acid
- ionise completely when it dissolves
- pH3 - weak acids - carboxylic acid
only a small part of the molecules
ionises eg. + photo
- both acids react in the expected with metals, alkalis and metal carbonates
How are esters formed?
- chemists react an alcohol with a carboxylic acid to make an ester and water
What are the stages to making an ester?
- Heating under reflux
- the alcohol and carboxylic acid are combined with sulfuric acid and heated under reflux - Distillation
the mixture is distilled after reflux
- Purification
Then an aqueous reagent is added to removw impurities from the ester
Shake it
4.Drying
granules of calcium are added to the mixture
- impurities to the surface
5. Distillation
the mixture is distilled again to increase the purity of the ester
What are alcohols and carboxylic acids in fats and oils?
- Alcohol is glycerol
- compound with three OH gruops
- carboxylic acids - long hydrocarbons attached to a carboxylic acid
What is an exothermic reaction?
- respiratin, combustion
- give out heat or energy
What is an endothermic reaction?
- photosynthesis
- takes in heat or energy
What is an energy change calculation?
eg. h-h=434kj
o-o=498kj
o-h=464
How can heating change a reaction?
gives atoms more energy to make collisions
eg. haeting decomposes blue copper sulfate crystals to give water and anlylrous copper sulfate, which is a white
Add water to the white powder after cooling it changes back into its hydrated form
As it does it turns blue again and gets very hot
How does concentration affect reactions?
-eg.
left to right = forward
right to left = backward
- forward
concentration of steam is high and the concentration of hydrogen is low
- Backward
the concentration of hydrogen is high and the concentration of steam is low
How is equilibrium reached?
eg. iodine is souble in a potassium iodide solution in water
- the aqueous solution of potassium iodide is yellowish brown
- iodine is also soluble in organic solvents(hexane) in which it forms a violet solution. Aqueous potassium iodide and the organic solvent don’t mix+photo
- start the experiment, with a test tube with a small crystal of iodine in hexane
- add potassium iodide
- no colour change as the iodide is dissolved in the hexane
- shake once
- iodide goes yellow and hxane goes purple
- shake twice - violet- hxane
- yellowish brown - iodide
+photo Graph 1
+photo formula
- experiment can be repeated wiht the iodide being dissolved in the iodide first, the hexane added and the result is the same
- a reversible reaction
What does the experiment tell us about equilibrium?
- at equilibrium the concentration of reactamts and products do not change
- An equilibrium state can be approached from either the reactant side or the product side of the reaction
How is ammonia produced?
- using the Harber process
- reversible reaction between nitrogen and hydrogen gas
1. reactants compressed to about 200 times atmospheric pressure - haeted to about 450 celcius and passed over an iron catalyst
- 100%
- 15% yield
- process needs to be economical without using too much energy
+photo of the process
How does pressure affect the Harber process?
- increased pressure, increases production of ammonia but this means less hydrogen + nitrogen is recycled
How is nitrogen gas fixed?
- nitrogen fixed by bacteria in the roots of plants
How is paper chromatography done?
- Paper chromatography
- mobile phase= solvent
- small amounts of the substances are applied to the paper
- solvent moves up the paper and the chemicals move
- each chemical has a dynamic equilibrium
eg. distribution of molecules between the paer and the solvent - if the chemical is more attracted to the mobile phase, moves faster, yet if more attracted to the stationary phase more slower
- chemicals seperate
What is a chromatogram?
- add substance to solvent
- put solvent in a chromatography tank and put a lid over it
- after a few minutes put a prepared paer( maked with a base line and spotted)or TLC
- all over the paper, but only above the baseline - solvent rises up the paer, leaving a sustance that can be analysed
What is the process of GC?
mobile phase: carrier gas(helium0
stationary phase: thin film of a liquid on the surface of powdered soil, packed into a sealed tube column
- some compound carried move slowly than others
as they have different boiling points or greater attraction to the stationary phase
- very small smaples needed
How are GC chromatograms interpreted?
- detector sends signal to a recorder/computer
when compound appears
- each peak one compound
- position of each peak is a record of how long the compound took to pass through the column- the retention time
- height of the peak tells the amont of the compound
How are titrations performed?
- analyst used pipette(or burette) to transfer a fixed volume of liquid to a flask
eg. acid base titration- might be 20cm(3) of the acid solution to measured volume
2. add two drops of indicator
3. indicator turns sharply green - end point
How are solution accurately prepared?
solution of sodium carbonate
- accurately weigh the sodium carbonate
- dissolve it in a small amount of solvent
- tranfer the solution to a graduated flask
- Rinse al the solution into the flask with more solvent
- add solvent drop by drop to make up the volume to the mark on the flak
- put a stopper on the flask and shake the flask
