Chemistry Unit 3 Flashcards
State what a fuel is
Fuels are substances that have stored energy and when burned, release this energy .
Name the three fossil fuels
Crude oil
Coal
Natural gas
Describe how fossil fuels are formed
Formed from animals and plants that where formed in the earth’s crust millions of years ago that contain carbon and hydrogen
Explain what is meant by the term finite with reference to fossil fuels
Finite means that something has only a limited supply, and so you could refer to fossil fuels as finite because they only have very limited supply
Are fossil fuels hydrocarbons?
Yes
However they have only minor impurities
What is crude oil a mixture of and what does it need to do for it to become useful
It is a mixture of hydrocarbons and it needs to be seperated to become useful
Describe the process of fractional distillation
fractional distillation is a process of crude oil being separated into different parts called fractions, in order to become useful
Describe what is meant by a fraction
A fraction is a group of hydrocarbons which have similar boiling points
Name the seven fractions in order from highest to lowest boiling point
(Highest)
-Gas
-gasoline
-naptha
-kerosene
-diesel oil
-lubricating/fuel oil
-residue
(Lowst )
Be able to describe the seven fractions trends in their properties
Lowest: Smallest molecules. Lowest boiling point Lowest viscosity. Lightest in colour.
Highest:Largest molecules. Highest boiling point. Highest viscosity. Darkest in colour.
as you get higher and higher in the fractional coulomb, the bigger you get a bigger, boiling, point, viscosity, molecules etc
State a use for each of the fractions
-Gas: bottled gas
-Gasoline: fuel for vehicles
-naphtha : plastics
-kerosene: fuel for aircrafts
-Diesel oil : fuel for vehicles
-lubricating oil: protects things from rust
-residue : roads
State the products of complete combustion of a hydrocarbon and how to test for them
word equation:
Methane+Oxygen—->Water+Carbon Dioxide
Products: water, Carbon dioxide
Tests:
H2o: cobalt chloride paper turns from blue to pink
Co2: turns limewater cloudy
State the products of incomplete combustion of a hydrocarbon
Word equation:
carbon—–>soot +carbon monoxide
Products:
soot, carbon monoxide
Describe the purpose of catalytic converters in reducing toxic emissions from car exhausts
The catalytic converter is a machine that fits into a car’s exhaust and converts the chemicals thats are bad for the environment (carbon monoxide)into less toxic pollutants. A three
way catalytic converters chemical formula is:
NOx—Nx+Ox
Explain why combustion is described as an exothermic reaction
It is because combustion releases energy when burning fuel in oxygen
Draw the fire triangle and use it to explain how fires are put out
desription: a triangle with the words heat, fuel and oxygen written on each side
there are 3 things a fire triangle needs to burn- these are the 3 sides of the triangle.
In order to extinguash a fire you need to remove one side of the trangle.
State the problems caused by the emissions from burning fossil fuels
Acid rain, global warming
Describe the carbon cycle
nature’s way of reusing carbon atoms, which travel from the atmosphere into organisms in the Earth and then back into the atmosphere over and over again
Describe the impact of burning fossil fuels on the carbon cycle
Because fossilised animals and plants contain carbon dioxide, burning them releades them back into the system, creating a rise in carbon dioxide in the atmosphere
Describe solutions to reduce the amount of carbon dioxide released from burning fossil fuels including carbon capture.
Choosing low carbon travel options(flying less)planting more trees, carbon capture, and eating less meat
Describe the production of biofuels such as biogas, bioethanol and biodiesel
biofuels are produced by using microorganisms to anaerobically ferment carbohydrate in the plant material
State what a hydrocarbon is
Hydrocarbobs are molecules which only contain the elements hydrogen and carbon
Name alkanes (up to eight carbons, C8)
-Methane-C1
-Ethane-C2
-Propane-3
-Butane-C4
-Pentane-5C
-Hexane -C6
-Heptane-C7
-Octane-C8
State the general formula for alkanes and use it to determine the molecular formula if given the number of carbons or hydrogens
CnH2n+2
Describe properties of the alkane family
-Their name ends in -ane
-they only contain carbon to carbon single bonds
-They burn to produce Co2 and H2o
Name alkenes (up to eight carbons, C8)
-Ethene-C2
-Propene-C3
-Butene-C4
-Pentene-C5
-Hexene-C6
-Heptene-C7
-Octene-C8
State the general formula for alkenes and use it to determine the molecular formula if given the number of carbons or hydrogens
CnH2n
Describe how to test for unsaturation
The organic compound to be tested is taken in a test tube. Dissolve it in 2ml of distilled water. Add bromine water drop wise with constant shaking. If the orange red colour of bromine disappears then the given organic compound is unsaturated.
State the definition of a homologous series
It is a series is a family of compounds which have the same general formula and similar properties
What are plants a good source of and what can they be used for?
a good source of carbohydrated and can be used for food and fuel
State which elements carbohydrates contain
Carbon, Hyrogen, and Oxygen
Describe the ratio of hydrogen to oxygen in carbohydrates
hydrogen to oxygen is 2:1
describe the process of and write a word equasion for fermentation
word Equasion: Glucose—>Ethanol+ carbon dioxide
In fermentation glucose is converted into ethanol by enzymes present in yeast. Carbon dioxide is gas is also produced
Explain how starch is related to glucose
Starch is a chain of glucose molecules which are bound together, to form a bigger molecule
Explain how to distinguish between glucose and starch using chemical tests
A chemical test for starch is to add iodine solution (yellow/brown) and look for a colour change. In the presence of starch, iodine turns a blue/black colour. It is possible to distinguish starch from glucose (and other carbohydrates) using this iodine solution test
Explain what happens to starch during digestion
Starch is insulable in water because it is too large to dissolve so it breaks down in to glucose which is much smaller and able to digest
What has to be present in yeast are required for fermantation to occour?
Enzymes
Explain why the ethanol concentration which can be produced during fermentation is limited
high concentrations of alcahol destroys enzymes and kill the yeast cell
Explain the process of distillation with reference to alcoholic drinks
Distillation is the process of separating alcohol from water via evaporation and condensation. The base alcohol is heated, and certain parts of it are captured. This process purifies and concentrates the remaining alcohol, which will ultimately be the final spirit produced.
How is the alcahol content of drinks measured?
in units
Give some examples of general products which are made by chemists using plants
-Oils
-Resins
-Natural rubber
Give specific examples of medicines and the plants they come from
Asprin-willow trees Morpheine-poppy