Flashcards in C1f Deck (12):
What are the conditions needed for cracking?
Why is cracking done?
-to help match supply and demand
-there is a higher supply of bigger hydrocarbons in crude oil than the demand for them
-so they are cracked into smaller hydrocarbons to meet the demand for them, as the original supply was less
What is cracking?
-splitting long alkane molecules into smaller alkane and alkene molecules
How can oil cause political problems?
-prices rise as stocks are used up, countries with big stops may start keeping more for themselves instead of selling
-countries with most oil and natural gas will have power over other countries. They can choose who and who not they supply to, inciting political conflict and even war
-harder for countries without lots of oil to get a hold of it, we may depend on politically unstable countries and our supply could be cut off at any time
How can oil cause environmental problems?
-oil tankers crashes, oil floats on water and spreads out by the waves and tides into a big oil slick
-oil covers sea birds' feathers, stopping them being waterproof, water soaks into feathers and they die of cold (also, birds can't fly with oil matted wings)
-detergents used to clean oil slicks break oil into droplets and make it easier to disperse (some harm wild life, can be toxic to marine creatures like fish and shellfish)
What needs to be considered when picking the best fuels?
-storage (if flamable or explosive it needs to be stored safely)
-ease of use (whether is lights easily and or move it safely)
What is complete complete combustion?
-when there is plenty oxygen
-complete combustion of any hydrocarbon will produce only carbon dioxide and water
-has a blue flame
What are the benefits of complete combustion?
-clean and non-poisonous
-lots of energy produced
What is incomplete combustion?
-when there isn't enough oxygen
-carbon monoxide and carbon are produced
-smoky yellow flame
What are the disadvantages of incomplete combustion?
-black carbon is sooty
-carbon monoxide is poisonous, colourless and odourless
What is the process of cracking?
-vapourised hydrocarbons pass over a powdered catalyst at 400C-700C
-aluminium oxide is the catalyst
-the long chains split on the surface of bits of catalyst