Revision Document Covering many different areas of chemistry - Includes:
- Flame Tests
- Metal Hydroxide Tests
- Test for Negative Ions
- Test for Halides
- Using Earths Resources
- Alkanes
- Alkenes
- Life Cycle Assessment
Collision theory is the amount of collisions per unit time.
There are many things which increase the rate of reaction, these are things such as:
Increasing the pressure, which will in turn increase the amount of collisions as there are
more particles which can collide.
Increasing the temperature, this will increase the energy which the particles have so they
move at a faster rate which means that there will be an increase in collisions.
Increasing the surface area, this means that there is a larger amount of surface which the
particles can collide with which will increase the surface area.
Variables:
Independent variable, the thing in the experiment which is changed.
Dependent variable, the thing which is measured.
Control variable, the thing in the experiment which is kept the same.
Reproducible, other people get the same results.
Repeatable, you get the same results each time.
Drawing a graph, the time always goes on the x axis which is the independent variable.
When measuring the rate of a reaction at a certain point, then a tangent should be drawn
touching the line of best fit at the point at which you are wanting to measure and then should
work out the gradient by doing y divided by x.
When working out the rate of the reaction for a time period for example the first 30 seconds
then you should simply go across to 30 seconds draw a line up to the line of best fit and then
go across the x axis and read the value which is present.
When you are working out the rate of a reaction between for example 30 seconds and 40
seconds, work out the rate of reaction for the first 30 seconds and then the first 40 seconds
and then minus the rate of reaction at 40 seconds by the rate of reaction at 30 seconds.
Hypothesis, a hypothesis is an idea which can be tested.
Rate of reaction = amount made divided by time.
Activation energy is the amount of energy which is required to start the reaction, this
activation energy can be lowered through the use of a catalyst.
, Accurate, how close you are to the right answer, the way in which the accuracy of a result
can be improved is through eliminating anomalous results and calculating a mean. This is
also so that the results can be compared.
Precise, the results were close together.
Describing the rate of a reaction of a graph.
The rate of reaction is the highest at the start as the line of best fit is the steepest, then the
rate of reaction slows down and then eventually stops at 50 seconds.
Exothermic, there is a release in energy, also represented as a decrease on a graph.
Endothermic, energy is taken in and is gained.
Chemical Analysis.
Flame Test, the method for a flame test is simple. First clean the wire loop through the use
of an acid and hold the wire over the flame until it is cleaned. Then dip the wire loop into the
substance which is being tested, then place the wire loop over the flame and observe the
colour of the flame which is produced.
Lithium - Crimson
Sodium - Yellow
Potassium - Lilac
Calcium - Orange, red
Copper - Green
Metal Hydroxide test, add a few drops of acid and then react with sodium hydroxide.
Aluminium - White precipitate, also if more sodium hydroxide is added in excess then the
precipitate will dissolve.
Calcium - White precipitate - Does not dissolve if more sodium hydroxide is added in excess,
conduct a flame test to identify substance.
Magnesium - White precipitate - Does not dissolve if more sodium hydroxide is added in
excess, conduct a flame test to identify substance.
Copper III - Blue precipitate
Iron II - Green precipitate
Iron III - Brown precipitate
Test for negative ions,
Carbonate ions, if there are carbonate ions present then the substance will bubble and
produce co2 gas. Additionally, if co2 is present then when bubbled through limewater then
the limewater will turn from clear to cloudy.
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