Topic 9 - Separate Chemistry 2 Flashcards
Nano
1 billionth
1 nanometer
1 x 10^-9 meters (.000000001m)
size of a pinhead
1 million nanometers
Applications (Glass)
On GLASS: Titanium oxide nanoparticles trigger a chemical reaction that breaks down dirt when the sun shines on it and when it rains the water lands on the glass and washes off the broken down dirt.
Applications (Cosmetic Industry)
Nanoparticles absorb deeper into the skin.
Application (Cancer fighting drugs)
Gold Nanocages carry the drugs to the tumour. They are strong yet light.
Risks of nanoparticles
More and more Nanoparticles in the ATMOSPHERE.
What is a functional group?
A group of atoms in a molecule that determines how that molecule’s chemical properties
State the functional group of alkanes
(C-C)
State the fucntional group of alkenes
(C=C)
What is are isomers? (2)
Molecules with the same molecular formula but different arrangements of atoms
Draw Ethane, Ethene, Ethanoic acid, Ethanol, Ethyl Ethanoate and both the repeating unit and section of poly(ethene)
Check image
Why can’t but-3-ene exist?
but-3-ene is just but-1-ene with the functional group on the other end of the molecule (isomers are numbered starting from the end closest to the functional group)
What are the products of the complete combustion of hydrocarbons?
Carbon dioxide and water
What defines complete combustion?
The full oxidisation of every atom in the hydrocarbon
What products can also be produced in the incomplete combustion of hydrocarbons?
Carbon monoxide (toxic) and soot/carbon (orange flame test)
What does bromine water test for?
unsaturated molecules
What happens in the bromine water test?
the bromine water decolourises from orange-brown to clear as the bromine undergoes an addition reaction with the unsaturated molecule forming a colourless product and removing bromine from the solutin
What product is formed when ethene reacts with bromine?
1,2-dibromoethane (1,2 means that there are TWO bromine atoms are attached to ONE carbon atom EACH)
Define an addition reacyion
A reaction where reactants combine to form one larger product molecule and no other products
Describe the fermentation process to produce alcohol (5)
Crush plant material to form a sugar solution. Add sugar solution (eg glucose) to a jar with yeast. Place airlock on jar to create an anaerobic environment but allow carbon dioxide to escape. Keep jar at 35 degrees and control pH to maintain optimums for yeast. This produces alcohol with a concentration of up to 15%
Describe the fractional distillation of ethanol (4)
The ethanol solution is heated. The heated liquid evaporates and their vapours cool as they rise up a fractionating column. As ethanol has a lower boiling point than water (78 degrees), it remains a gas for longer, and so separates from the water. This separated solution then condenses and is collected
State the general formula of alchols
CnH2n+1OH
State the functional group of alcohols
OH
Describe the chemical properties of alcohols (3):
Produce carbon dioxide and water on complete combustion. Can be oxidised to from carboxylic acids in the presence of oxidising agents such as hot copper oxide. React with reactive metals such as sodium, forming hydrogen gas as one of the products
How does chain length affect alcohol reactivity with sodium?
The shorter the chain length, the more reactive
State 5 uses of alcohols:
Solvents, Cosmetics, Recreation, Varnishes, Bio-methanol and bio-ethanol are renewable fuels
State the functional group of carboxylic acids:
-COOH
State the general formula of carboxylic acids
CnH2n+1COOH (where n is number of carbons - 1) OR CnH2nO2
What is the relationship between carbon chain length and acidity in carboxylic acids?
The shorter the chain length, the more acidic
What is the pH range of carboxylic acid solutions?
3-6
Describe four carboxylic acid reactions:
- CA + metal —> salt + hydrogen. 2. CA + base —> salt + water. 3. CA + carbonates —> salt + water + carbon dioxide. 4. CA + oxide —> salt + water
What happens to a carboxylic acid in solution?
The COOH group forms a H+ ion while the rest of the molecule forms the negative ion (salt). This is because hydrogen is less reactive than the metal.
Naming salts
Metal + acid prefix + -anoate (eg, ethanoic acid + lithium —> lithium ethanoate + hydrogen)
Carboxylic acids are weak acids. What does this mean?
Weak acids are acids which do not fully dissociate in solution to form the max number of H+ ions
What is a polymer?
A large molecule made from lots of repeating monomers joined togetehr
Why can’t polymers be given specific relative molecular masses?
They can be different lengths, and so contain differing numbers of atoms
What determines a polymer’s properties?
The monomer it is made from
State three polymers, their monomers and whether they are natural or not:
- Protein - amino acid - natural. 2. Plastics - it depends - synthetic. 3. DNA - nucleotides - natural
Define addition polymerisation
A reaction in which monomers join together to form only one product: a polymer.
Describe the addition polymerisation of ethene and how you would draw it (2)
One of the bonds in the double bond in ethene breaks open and another ethene molecule joins on. This process repeats with many monomers
State the properties and uses of poly(ethene)
Flexible (cling film) cheap (plastic bags) good insulator (poly tunnels)
State the properties and uses of poly(propene)
Flexible(ropes) can be spun into fibres(carpet) Shatterproof(buckets)
State the properties and uses of poly(chloroethene)
Tough(windows) can be hard(gutters) good insulator(wiring insulation)
State the properties and uses of poly(tetrafluoroethene)
slippery(non-stick utensils and pans), water resistant(coatings on clothes)
State 5 problems with synthetic polymers:
Most are not biodegradable(cannot be broken down by microbes). Most cannot be recycled, so go to landfill. All produce carbon dioxide (greenhouse gas) and some produce toxic substances when burnt. Most are made from crude oil. Wildlife can get tangled in/ingest them
State 2 advantages of synthetic polymers:
Not biodegradable, so last long. Some can be recycled
Describe the steps to recycle a polymer (6)
Collect waste. Sort waste by hand into different types. Dispose of non-recyclables in landfill. Clean polymers and grind into chippings. Purify chippings. Melt chippings and process into new products
What is condensation polymerisation?
A process in which monomers join together to form a polymer and eliminate a small molecule, such as water
What are plastic bottles made from and why?
PET (a polyester) because it is strong, light, shatterproof and recyclable
State the functional group of esters:
-COO-
How are esters formed?
By a condensation reaction when a carboxylic acid reacts with an alcohol in the presence of a catalyst. Carboxylic acid + alcohol —> ester + water
What molecules do you need to form polyesters?
Diols and dicarboxylic acids so an ester link can form on both sides of the ester
Describe what happens in condensation polymerisation (2)
The oxygen and hydrogen from the carboxylic acid COOH group and hydrogen from the alcohol OH group join to make H2O. The remaining carbon and oxygen from the carboxylic acid COOH group and oxygen from the alcohol OH group join together to form an ester link, pulling the carboxylic acid and alcohol together to form an ester
How do you name esters?
Start with the name of the alcohol, change the ending from -anol to -yl and add the name of the carboxylic acid with -anoate instead of -anoic Example: ethanol and ethanoic acid gives ethyl ethanoate
Name two types of condensation polymer:
Polyesters and Polyamides
State the balanced equation for the fermentation of glucose to produce ethanol
C6H12O6 —> 2C2H5OH + 2CO2
what is feedstock?
A raw material used to provide reactants for an industrial reaction.
Flame test process
Dip nichrome wire loop in HCl, then distilled water, then into the metal compound. Hold metal compound in flame and note the colour
Lithium flame colour
Crimson/red
Sodium flame colour
Yellow
Potassium flame colour
Lilac
Calcium flame colour
Orange-red
Copper flame colour
Green-blue
Metal hydroxide test
Add an excess of sodium hydroxide to each metal compound.
Aluminium, metal hydroxide test
White precipitate formed, dissolves to colourless in excess NaOH
Calcium, metal hydroxide test
White precipitate formed
Copper, metal hydroxide test
Blue precipitate formed
Iron (II), metal hydroxide test
Green precipitate formed
Iron (III), metal hydroxide test
Brown precipitate formed
Test for halide ions
Add dilute nitric acid followed by silver nitrate solution
Chloride test result
White precipitate formed
Bromide test result
Cream precipitate formed
Iodide test result
Yellow precipitate formed
Test for carbonates
Add dilute HCl, if a carbonate is present then there will be fizzing.
Why does the carbonate test fizz if positive?
If a carbonate is present then it will react with the acid and produce CO2.
Test for sulphate ions
add dilute hydrochloric acid followed by barium chloride solution
Positive sulphate test result
White precipitate formed
