Important points physics. chemistry and mathematics
1. Important Points
Chemistry
Unit 1
• Salt preparation:
o For example, the reaction between Copper(II)Carbonate(Cu2SO4) and Sulphuric acid
• Observations of alkali metals:
o Lithium
Gas given off
Fizzing/effervescence
Floats on top of the water
o Sodium
Gas given off
Melts into a ball
Floats on water
Fizzing/effervescence
o Potassium
Gas given off
Very fast reaction, in comparison to the other 2
Purple/lilac flame given off
Morphs into a ball
Floats on top of the water
• When carrying out an enthalpy reaction which involved an exothermic reaction that releases
heat, we take a series of temperatures. This is because:
o Any fluctuations in temperature smoothed out
o Able to allow for cooling effect
• Poly(propene) does not have a sharp boiling point because poly could mean different chain
lengths.
Unit 2
• Indicators
o Litmus
Red in Acid
Green in neutral
Blue in Alkali
Range of pH 5 to 8
Link
o Phenolphthalein
Pink in Alkali
Colourless in acid or near neutral
Range of pH 8.3 to 10.0
Link
2. o Methyl Orange
Alkali or neutral is Yellow
Acid begins from Orange and works its way up to red
Range of pH 3.1-4.4
Link
o Universal Indicator
It is a combination of many different reagents, which include Methyl Orange
and Phenolphthalein.
pH Description Colour
0-3 Strong acid Red
3-6 Acid Orange/Yellow
7 Neutral Green
8-11 Base Blue
11-14 Strong Base Purple
o From what we can see Litmus is an indicator for determining whether it is an acid or
base
o Phenolphthalein can be used to judge the strength of an alkali
o Methyl orange can be used to see the strength of an acid
• Homolytic and Heterolytic bond fission
o Homolytic is when a bond is cleaved, and each atom gets an electron
o Heterolytic is when a bond is cleaved, and one atom gets on electron and the other
does not get any.
• Reactions of Halogenoalkanes
o Substitution
Happens when KOH/NaOH is dissolved in H2O
Also, dilute KOH and NaOH Both happen
o Elimination under reflux.
Happens when KOH/NaOH is dissolved in Alcohol
Also concentrated KOH and NaOH
o Reaction with Ammonia
This is a special case, because this happens in a sealed tube, as if it were to
happen under reflux, then NH3 would leave the condenser as it simply does
not condense.
• Frequently asked bond angles
o FBF
120o
o NHN
107o
o HOH
104.5o
• Molecules with H-Bonding
o Molecules with N-H bonds, such as NH3
o Molecules with O-H bonds, such as H2O and C2H5OH
3. But Hydrogen bonding in H2O is stronger than in Ethanol, because the
hydrogen bonding is limited by the fact that there is only one hydrogen in
each ethanol molecule with sufficient δ+ charge, whereas, in water, there
are 2 hydrogen with δ+ charge, thus allowing more bonds to be formed.
o Molecules with H-F, such as HF
The Maxwell-Boltzmann distribution diagram
Fewer molecules will have the activation
energy, because there is less kinetic
energy due to a lower temperature. 500oC
At lower oC, the
curve will shift to
the right.
• Iodine and Sodium Thio-sulphate titrations
o The indicator used to find the end point of the titration is Starch.
• Balancing Ionic Equations and Overall Equations
o When doing this, only certain particles can be added
-
Electrons (e )
Water Molecules (H2O)
+
Protons, or Hydrogen ions (H )
-
When balancing alkaline reactions, OH ions can be added
o You first have to balance the electrons, by multiplying one side by two different
integers
o Then cancel the H+ ions and H2O on both sides
o Then the equations should be balanced
• The boiling point of substances
o It all depends on the intermolecular forces
o In a question, when the only variable is the chain-length, then the longest un-
branched chain will have the highest boiling point.
o If there is a functional group, such as –OH, then this will be the choice, as normally in
organic molecules without special functional groups, there are only London forces.
But in alcohols, there are also dipole forces.
4. o A typical example:
The correct answer is D. Because it has –OH and also, the alcohol is primary. In secondary alcohols,
the –OH is cluttered by hydrogen atoms, thus the intermolecular bonding is less effect than in D.
Unit 3
• Enthalpy Change reactions (EDEXCEL_JUN_09_3B_2)
o If, in a reaction, a metal is involved, often the mass of the metal is not taken into
consideration when measuring the enthalpy change, because the specific heat
capacity of the metal is negligible.
o The reason why the experiment is continuously stirred is to spread out the
temperature more uniformly, also to make sure that all the reactants have reacted.
o The greater the enthalpy change, the greater the difference in reactivity between
the reactants(c).
• The way to distinguish halides using sulphuric acid
o A chloride, such as Lithium Chloride would give out white/steamy fumes.
o A bromide, such as Sodium Bromide would give out brown/orange vapour or liquid.
o An Iodide, such as Potassium Iodide would give a purple vapour / dark solid or liquid
or residue.
5. Physics
Unit 1
• The point beyond the elastic limit is called the yield point, here there is a large increase in
strain for a small increase in stress, meaning that for a small force there is a large extension.
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Figure 1: Properties of Materials Stress-Strain graph Document
• Streamlined flow or laminar flow is flow that has no abrupt change in direction or speed of
low, usually this occurs at low speeds. Streamlines do not mix.
• Turbulent flow is flow in which there is abrupt change in speed and direction and thus
causes the formation of eddies. Comment [R1]: In fluid dynamics, an eddy is t
swirling of a fluid and the reverse current created
when the fluid flows past an obstacle.
6. • The major difference between ductile and malleable is that the forces of attraction in
malleable materials are weak and thus they can be moulded into shape. But, in ductile
materials, the material has empty spaces between the particles in the materials. So ductile
materials can be stretched into lines.
• Tough materials are those that absorb a lot of energy
before breaking. But hard materials cannot, they cannot
absorb energy much, but they can withstand large
impact forces, i.e. they are hard to scratch or indent.
• A strong material is a material that requires a large stress
to break it.
• A hard material is a material with high breaking stress,
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• Compressive strain:
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• Compressive Stress:
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Figure 2: PH01_0906_14-15_Worked
• Often, a data logger is used, because it can accurately record large amounts of data in real
time, so it is easier to process, and reduces the chances of human error.
Unit 2
• A source of light emits a train of waves lasting 0.04 μs. The light has a wavelength of
600 nm and the speed of light is 3×108 ms-1. How many complete waves are sent
out?
A. 2.0 × 107
B. 4.5 × 107
C. 2.0 × 1010
We need to keep in mind the values of ������ and n, ������=10-6 and n=10-9
D. 4.5 × 1010
The total length for the ray of light is 0.04 × 10−6 × 3 × 108 = 12������
o
∴ ������������������ℎ ������������������������ ������������������������������ 600 × 10−9 ∴ 12 ÷ 600 × 10−9 = 2.0 × 107
o
o
7. o The single resistor will have 2X the current.
o Therefore, as P=I2R, current will be made four times, and therefore quadrupled.
o This is in comparison to one of the two resistors, not both of them.
o Thus, the first will have 4 times than one at the bottom as 2 is squared.
How much electrical energy is required to move 4.00 mC of charge through a potential
difference of 36.0 V?
A. 1.11 × 10-4 J
B. 0.144 J
C. 144 J
D. 9000 J
Remember that ������ =
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•
• NTC resistors decrease their resistance as the temperature increases
• As the voltage increases, so does the temperature of the NTC resistor
• As we can see that the curve becomes steeper, so for a larger value of V, there is a greater
Thus, the answer is B. Because ������ =
������
increase In I than R, which is the gradient
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•
• Another interesting question is Question 8_SAM_GCE_UNIT2
8. , ������������ 1�8 ������ℎ, ������������ ������ ������������������������������������������������ ������������������������ ℎ������������ ������ ������ℎ������������������ ������������ 2������
������
4
So, 0.5 × 8 = 4, ������������ ������ℎ������ ������������������������������������������������������ℎ
•
This as ������ = ������������, ������ = 10 × 4 = 40 ������������ −1
•
•
• The rate at which electrons are liberated due to the photoelectric effect, from a metal
surface is depends on the distance between the source of light and the metal surface. Thus,
the number of photoelectrons emitted only depends on the intensity, not the frequency.
• UV light only transfers energy to the metal surface, not electrons, so on a positively charged
metal surface, on an electroscope, it would have no effect.
•
• The difference between sound waves and radio waves:
Radio Waves Sound waves
1. Transverse 1. Longitudinal
2. Travels through Vacuum 2. Travels through medium
3. Much faster than sound 3. Much slower than radio
4. Infinite range of frequencies 4. Frequencies between 20Hz-20KHz
9. This question is taken from Edexcel June
2009 Physics paper2. Section A question 2.
have a speed of 3 × 108 .
• The higher the frequency, the lower the wavelength, because all electromagnetic waves
• As ������ = ������������, i.e. ������������������������������������������������ = ������������������������������������������������������ × ������������������������ − ������������������������������ℎ
10. Unit 3
This Value is the mode, and the
other value, thus has a chance of
being an error.
The equipment used is not has errors. The piece of equipment most probably used is a micrometer
which has a percentage error. The actual reading is too far away from the ones obtained, so not C. D
is also not the answer because the actual reading is to one decimal place as well. It is not A, because
the students recordings are very close to each other, and therefore we may presume that he/she has
made very few mistakes. Thus leaving B, as the most logical conclusion.
11. Business Studies
Technique
• Whenever reading through a case study, try to understand the motives of the business, and
evaluate the position from their point of view.
• When answering a context in Edexcel, these are the guidelines that you have to follow:
o Knowledge, most of the time, this is a definition
o Application
o Analysis, this is where you analyse the data
o For higher marked questions, there will be an evaluation.
• This is an example of the shorter questions:
• Examine one way in which Innocent Drinks achieved a competitive advantage.SAM 9(b) [6]
• Competitive advantage is any feature of a business that allows it to compete effectively. In Comment [R2]: Knowledge. Here we have
defined what Competitive advantage means.
this case, the endorsement by Coffee Republic, by stocking their goods. As Coffee Republic is
Comment [R3]: Application of your knowledge
an established brand, having many stores, this would mean that more people will have a
chance to try out the product, so it would raise consumer awareness. Furthermore, as a Comment [R4]: Analysis1, the advantages of
having Coffee Republic help you out.
brand has endorsed ID, that in itself is an as now a brand image is attached to their name.
Comment [R5]: Analysis2
Answering MCQs in both Unit 1 and Unit 2
From Edexcel Business Studies June 2009 Unit 2
6. Chocolate maker Green & Black’s objective is to increase profit. Comment [R6]: Key term
(a)Which one of the following is most likely to be the best tactic? [1] Comment [R7]: Key term
(b)Explain why your answer is correct? [3]
• The first mark would be a mark for knowledge, so the definition of either tactic or profit
would be acceptable, as they are key terms in the question. So, thus would be the
knowledge mark
• The second mark would be an explanation as to why you chose D, thus showing your
understanding, a third mark could also be scored out of this
• However, easier way of getting a mark is to explain why the other options are wrong, so for
example why would ceasing advertising be the wrong thing to do.
• But, there is a fundamental mark for why you chose your option. The other two marks are
optional marks, they can be gained from further explaining your choice or the application of
your knowledge
12. Unit 1
• Competitive advantage: Any feature of the business that enables it to compete effectively.
It may be based on price, quality, service, reputation for innovation of the product.
• Also, in Dave Hall defined as an advantage which allows the business to perform better than
its rivals.
• The difference between Unique Selling Point and Competitive advantage is that a unique
selling point may provide a competitive advantage, meaning that it is a feature that may give
the business a competitive advantage. So, it is a PART of competitive advantage. Or, a
feature of the business that may provide a competitive advantage.
• Usually the term USP is referred to niche markets and Competitive advantage to mass
markets.
13. S1
Coding
• Mean
o Affected by all, to calculate the actual mean, just equate it back through the coding
• Standard Deviation
o Just affected by division and multiplication
o Just multiply it by the factor you divided by, and vice versa
• Product moment correlation
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o Not affected
•
o This is affected by all, just equate a and b back through the equation
• Variance
o Affected by what you have multiplied it by, and nothing else.
o If Var(a+bx)
o Then the answer would be b
M1
Vectors
• When something is due south or due north of a point.
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• Whenever calculating the acceleration in Chapter 3 question, always calculate them for the
entire body at all times.
C3
Trigonometric Identities