Chemistry Revision

Flashcards by HeyItsNathan, updated more than 1 year ago
Created by HeyItsNathan over 7 years ago


These cards will go over the answers for the National 4/5 Chemistry Unit 2a which can be used for revision.

Resource summary

Question Answer
What is meant by Combustion: Combustion is a chemical reaction that occurs between a fuel and an oxidizing agent that produces energy, usually in the form of heat and light. What is meant by a fuel: Any material that can store potential energy that can be released and used as heat energy (their energy comes from the sun)
What is meant by a fossil fuel: A hydrocarbon deposit derived from living matter and used for fuel. How are fossil fuels formed: Fossil fuels are formed by natural processes such as anaerobic decomposition of buried dead organisms or plants.
Fossil fuels: Oil, Coal, Natural gas and Peat. Peat is the accumulation of decayed plants. Non-fossil fuel: Wood, biomass and hydrogen. Biomass is a material derived from living or recently deceased organisms, such as wood and alcohol fuels.
Three requirements for a fire to begin: Oxygen, Heat and a Fuel. What is a hydrocarbon? A hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. ONLY hydrogen and carbon.
What is the difference between complete and incomplete combustion: Complete combustion released carbon dioxide and water, whilst incomplete released carbon dioxide, water AND carbon monoxide. A poisonous gas produced by incomplete combustion of hydrocarbons: Carbon Monoxide.
What poisonous gas is produced by fuels containing sulphur: Sulphur Dioxide What is formed when Sulphur(g) dissolves in water? It can form acid rain.
Some harmful environmental effects of acid rain: It can cause acidification of lakes and streams, and it can erode building materials. Two ways of reducing the levels of carbon monoxide: Fitting catalytic converters to cars, and improving the efficiency of combustion by increasing the concentration of oxygen.
What is meant by a finite source of energy and a renewable source of energy? Finite = it cannot be replaced once it is used Renewable = It can be constantly replaced. Finite and renewable energy: Finite = Oil, coal, natural gas. Renewable = wind, tidal, solar and wood.
What is meany by biomass: Plant or animal based materials. Three examples of the use of biomass material as fuels: Ethanol, bio diesel and burning logs.
Two biofuels and how they can be produced: Ethanol can be produced from sugar canes. Bio Diesel can be produced from waste vegetables. What is meant by the carbon cycle: The sequence of processes through which carbon conpounds move from one place (such as a forest) to another (such as the atmosphere)
What is meant by a greenhouse gas: Any gas in our atmosphere that is capable of absorbing heat. The most significant one is water vapour that contributes around 80% of all greenhouse gases. What is meant by global warming, and what are the causes? Global warming is the rise in the average temperature of the Earth's atmosphere, and it can be caused by carbon dioxide and other air pollutants being collected in the atmosphere which trap the suns heat.
What is meant by our carbon footprint: The total sets of gas emissions caused by a product, person, organization or event. What is meant by carbon capture and storage (CCS) and why is it important: It is the process of capturing waste carbon dioxide, transporting it to a storage site and depositing it where it will not enter the atmosphere, and it is important as it reduces emissions and reduces the levels of global warming.
What is meant by distillation: A method of separating mixtures based on differences in the conditions required to change the components of the mixture. What is the boiling point of Water and Alcohol, and which boils off first: The boiling point of water is 100 degrees and for alcohol, 78 degrees. Alcohol boils off first.
Why is crude oil not of immediate use? It is a mixture of hydrocarbons and they need to be separated to become useful products. What is meant by fractional distillation? A process by which components in a chemical mixture are separated according to their different boiling points.
As the number of carbon atoms in a fraction increases, what happens to the colour and the ability of the fraction to ignite: It gets darker, and it is more difficult to ignite. What is meant by the viscosity of a liquid, and as the number of carbon atoms in a fraction increases, what happens to the viscosity of the fraction? The viscosity of a liquid is how thick or runny the liquid is, the more viscous means thicker, less viscou means more runny. And the viscosity becomes more thick.
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