Chemistry 1b Flashcards
How are long hydrocarbon chains broken down ?
Thermal decomposition
What is cracking ?
When you split a long-chain hydrocarbon to form more useful hydrocarbons.
Describe the process of cracking
- Hydrocarbon chain is heated
- Passed over aluminum oxide catalyst
- The molecules CRACK over the catalyst
What’s are the first two Alkenes ?
Ethene and propene
What is a way of testing if an oil is unsaturated ?
Bromine water
How does bromine water show if an oil is unsaturated ?
It reacts with the oil by opening the double bonds this decolorises the usual brown bromine water
What is ethene reacted with to make ethanol ?
Steam (H2O) - in the presence of a catalyst
True or False - ethanol made from ethene is used in alcohol
False
How is ethanol in alcohol made ?
Fermentation
What is a major use for Alkenes ?
Polymers
How are polymers made ?
By joining together lots of the same small alkene molecules to form very large molecules
What is the polymer made from…
Ethene
Propene
Polythene
Polypropene
How are polymers used ?
Give three examples
Plastic bags / milk cartons / credit cards / memory foam - any form of plastic
What is a big problem with polymers ?
They are not biodegradable
What Does the word ‘biodegradable’ mean ?
When something is broken down by bacteria
What are the two ways of extracting oil from plants or seeds ?
- Crushing and pressing
* Solvents
Explain the process of crushing to extract oil
- Plant material crushed, then placed between metal plates and squash the oil out
- It is then separated from the plant material in a centrifuge
What do oils provide when consumed ?
Energy
Why does cooking with oil speed up the process ?
They have higher boiling points than water, so they can be cooked at higher temperatures and therefore quicker
What does ‘monosaturisation’ mean ?
Fats contain one C=C double bond
Explain the process of hydrogenation
Hydrogenation is the process where unsaturated oils are hardened. The oils are reacted with hydrogen bubbles in the presence of a nickel catalyst at 60 degrees
What are trans fats and how do they occur ?
Trans fats are believed to be very bad for you, they are caused when you partially hydrogenate an oil
What do emulsifiers do ?
They make water and oil mix
What part of the emulsifier is hydrophilic (water loving) ?
The head
The …………. Is hydrophobic
Tail
How do emulsifiers help oil and water mix ?
The hydrophobic tails lath on to oil droplets however the hydrophilic heads stay in water. This keeps the oil in very small droplets which stops the oil forming layers, so it mixes
What was wegener’s theory ?
Continental drift
Explain continental drift
The idea that about 300 million years ago there was just one supercontinent called Pangaea. The continents we know today have DRIFTED apart
What evidence did he have of this ?
- Identical fossils of the same crocodile found in both South America and Africa
- Africa and South America se to fit together
- Matching rock types
Why was Wegener’s theory not accepted ?
- Wegener thought that they had move because of the tides however geologists correctly said this was impossible
- He made some of his numbers up
What are the three layers that form earth ?
Core, mantle and crust
What is the core made up of ?
Iron and nickel
What is the crust made up of ?
Tectonic plates
Where do volcanoes and earthquakes occur ?
Plate boundaries
Why can’t scientists predict earthquakes and volcanoes ?
Because it happens below the crust in the mantle, which we can’t see or measure
How do the plates move ?
Convection currents in the mantle cause the plates to move apart or close together
What did the early atmosphere mainly contain ?
CO2
How where the oceans formed ?
Water vapour released from volcanoes condensed.
How did oxygen enter our atmosphere ?
Plants and algae evolved and liked the CO2. Photosynthesis happens and O2 is released into the atmosphere
How did oxygen in the atmosphere allow complex animals to evolve ?
The oxygen formed the ozone layer which blocks harmful rays from the sun
What is the primordial soup theory ?
This was the theory that the atmosphere that was rich in nitrogen, hydrogen, ammonia and methane was struck by lightning causing a chemical reaction which formed amino acids.
What did the amino acids, millions of years ago, do ?
Gradually produced organic matter and later living organisms. They are the building blocks of life
Who carried out the primordial soup experiment ?
Miller and Urey
What is used, as well as Alkenes, to make biodegradable polymers ?
Cornstarch
