Fuels and Earth Science Flashcards

Question

Why are longer hydrocarbons cracked?

Answer 1

longer molecules are cracked into smaller molecules as there is a higher demand for products like petrol than products like bitumen, so more molecules are needed

Answer 2

aluminium oxide

Answer 3

1. alkane is heated until it is vaporised 2. vaporised hydrocarbons pass over a powdered catalyst (aluminium oxide) 2. the long-chain molecules split apart or "crack" on the surface of the catalyst - producing short-chain alkanes and alkenes

Answer 4

if one fraction is in high demand, the hydrocarbons from another fraction can be cracked to supply it

Answer 5

1. Volcanoes gave out steam and CO2 (Earth's surface was originally molten, eventually it cooled, forming a thin crust, but volcanoes kept erupting, releasing gases from inside, this degassing released mostly CO2, so things settled down and the early atmosphere was now mostly CO2 and water vapour which condensed to form oceans) 2. Green plants evolved and produced oxygen (a lot of CO2 also dissolved into oceans, Nitrogen gas arrived in the atmosphere after ammonia and oxygen reacted and it was released by denitrifying bacteria, this kept increasing as it was unreactive so couldn't be broken down, green plants evolved over the earth and photosynthesised, taking CO2 and making O2, oxygen levels increased and carbon dioxide decreased as it was locked up in sedimentary rocks and fossil fuels) 3. Ozone Layer allows evolution of animals (build-up of oxygen killed off early organisms but allowed the evolution of more complex organisms that used oxygen, oxygen also created the ozone layer that blocked harmful solar rays and enabled even more organisms to evolve, virtually no CO2 is left now)

Answer 6

test for oxygen by checking if the gas will relight a glowing splint

Answer 7

- growing population means more respiration so more CO2 - larger population means more energy is needed for lighting, cooking, heating etc and countries becoming richer and industrialised so average energy demand per person increases - increased energy consumption means more fossil fuels are burned so more CO2 is released - people take up more land so deforestation occurs - meaning less plants to take away CO2 - CO2 also produced by volcanic eruption

Answer 8

1. sun gives out EM radiation 2. most EM radiation passes through the atmosphere 3. some EM radiation (with short wavelengths) is absorbed by the Earth - warming our planet 4. the Earth radiates some of this heat radiation as infrared (which has a longer wavelength than the energy taken in) 5. some of this infrared radiation is re-emitted back into space, some is absorbed by greenhouse gases, and some is reflected back to Earth by these greenhouse gases - warming the planet 6. enhanced greenhouse effect occurs when more heat radiation is absorbed than sent back to space

Answer 9

gases in the atmosphere, present in small amounts, that absorb and reflect heat radiation

Answer 10

methane is an extremely effective greenhouse gas - concentration of methane has risen rapidly due to human activity e.g. farming as it is produced in the digestive processes of livestock e.g. cattle

Answer 11

that it is caused by humans

Answer 12

because data was taken over fewer locations and the methods used were less accurate - however analysis of fossils, tree rings and gas bubbles in ice can estimate CO2 levels but these are less precise and only include certain locations

Answer 13

- by cutting down the amount of greenhouse gases - limiting use of fossil fuels e.g. walking or turning down central heating - UK has plans to encourage energy efficiency by creating financial incentives to reduce CO2, using more renewable energy and increasing research into new energy sources

Fuels and Earth Science Flashcards

(37 cards)