Separate Chemistry 2 Flashcards
What colour flame does Lithium have
Crimson
What colour flame does Sodium have
Yellow
What colour flame does Potassium have
Lilac
What colour flame does Calcium have
brick red/ orangey
What colour flame Copper have
blue-green
How to carry out a flame test
Clean a nichrome wire loop by dipping it in HCl
Then dip into metal compound and place loop into the clear blue part of a bunsen flame
What colour precipitate does aluminium form
White
But dissolves with excess NaOH
How to test for metal ions that form precipitates
Add NaOH
What colour precipitate does Calcium form
White
What colour precipitate does Copper (2) form
Blue
What colour precipitate does Iron (2) form
Green
What colour precipitate does Iron (3) form
Brown
How to test for ammonia
add NaOH solution
If present then damp red litmus will go blue
How to test for halide ions
Nitric acid and then Silver Nitrate solution
What colour precipitates do the halides form when tested
Chloride - white
Bromide - cream
Iodide - yellow
How to test for carbonates
Add dilute acid
Then use CO2 test
How to test for sulfate ions
HCl and Barium Chloride
What colour precipitate will a sulphate form
White
What does flame photometry allow us to do
Identify ions in a mixture or in a dilute solution
How is it carried out
(flame photometry)
A sample is placed in a flame
The electrons are excited and as they drop back down to their original energy level the emit energy in the form of light
This passes through a spectroscope a a line spectrum is produced
What is flame photometry useful for
Concentration of ions in solution
Intensity of light
Intensity of solution
What are alkanes
Saturated hydrocarbons
Formula CnH2n+2
What are alkenes
Unsaturated hydrocarbons
Formula CnH2n
Test for alkene
Bromine water
Decolourise orange to colourless
What are addition polymers
Polymers made from unsaturated monomers (alkenes)
Uses of polymers
Poly(ethene) - Flexible, electrical insulator, cheap - used in plastic bags, bottles and wire insulation
Poly(propene) - flexible, strong, touch, mouldable - crates, furniture, ropes
Poly(chloroethene) (PVC) - tough, cheap - window frames, water pipes
Poly(tetrafluoroethene) - unreactive, tough, non-stick - non-stick pans, waterproof clothing
What type of monomer does polymerisation reactions involve
2 different types of monomer
What are polymers made from
Crude oil
Pros and cons of burning polymers
Pros:
Energy released can be used for electricity
Reduces volume of waste
Cons:
CO2 is made
Toxic gases are also made
Pros and cons of landfill
Pros:
Cheap
Easy
No need to sort waste
Cons:
Destroys environment
Waste is dangerous to animals
Eyesore
Pros and cons of recycling
Pros:
Conserves a vital raw material (crude oil)
Less waste to landfill
Cons:
Sorting plastics is time consuming
Expensive
What is the general formula of an alcohol
CnH2n+1OH
What happens to alcohols to form carboxylic acids
Oxidised
What happens if you meet a mixture of an alcohol and an acid catalyst
An alkene and water are formed
This is called a dehydration reaction
How are carboxylic acids similar to normal acids
React with carbonates to form CO2, salt and water
Can partially ionise in solutions
What is the general formula for Carboxylic acids
Cn-1H2n-1COOH
What is a substitution reaction
Where a H gets substituted by another atom eg. Bromine
This must happen under UV
Eg
CH4 + Br2 –> CH3Br + HBr
What is an addition reaction
When an alkene reacts with a halogen
The double bonds is broken and the halogen goes onto the 2 Cs with the double bond
eg.
C2H4 + Br2 –> C2H4Br
Equation for breakdown of glucose
C6H12O6 –> 2C2H5OH + 2CO2
What does the breakdown of glucose
Enzymes in the yeast
Examples of things that can be used for the glucose in production of ethanol
Sugar cane
Sugar beef
Grapes
Why is the concentration of ethanol around 10-20%
Because the yeast dies
What is used to concentrate the ethanol
Fractional distillation
Then a Leibig condenser
How to measure which alcohol is the most efficient fuel
Spirit burner with alcohol in it and use a mass balance to measure the mass
Measure 100cm^3 of distilled water into a copper calorimeter
Insulate the container
Cover with an insulating lid
Take initial temp
Light wick
Stir
When temp has increased by 20 degrees blow out the wick
Reweigh immediately
Repeat
What are the size of nanoparticles
1-100 nanometers across
What is a nanoparticle surface area to volume ratio like
High
Uses of nanoparticles
Catalysts (high SA to V ratio)
Cosmetics - eg. sunscreen
Electric circuits (conduct electricity)
Sports equipment plastics (durable and stronger)
What could potential problems of nanoparticles be
They don’t break down as easily so perhaps they could start to build up in cells and cause problems such as lung inflammation
What are composites
They are made of one material (the reinforcement) embedded in another (matrix)
What happens when ethanol + oxygen
Carboxylic acid formed
How are esters formed
Carboxylic acid + water
Characteristic smells
Insoluble in water
