58753902 important points physics chemistry and mathematics

8/4/2019 58753902 Important Points Physics Chemistry and Mathematics

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Important Points

Chemistry

Unit 1

y Salt preparation:o For example, the reaction between Copper(II)Carbonate(Cu2SO4) and Sulphuric acid

y 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

y When carrying out an enthalpy reaction which involved an exothermic reaction that releasesheat, we take a series of temperatures. This is because:

o Any fluctuations in temperature smoothed outo Able to allow for cooling effect

y Poly(propene) does not have a sharp boiling point because poly could mean different chainlengths.

Unit 2

y Indicatorso Litmus

Red in Acid Green in neutral Blue in Alkali Range of pH 5 to 8 Link

o Phenolphthalein Pinkin Alkali Colourless in acidornearneutral Range of pH 8.3 to 10.0 Link


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o Methyl Orange Alkali or neutral is Yellow Acid begins from Orangeand 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 orbase

o Phenolphthalein can be used to judge the strength of an alkalio Methyl orange can be used to see the strength of an acid

y Homolytic and Heterolytic bond f issiono Homolytic is when a bond is cleaved, and each atom gets an electrono Heterolytic is when a bond is cleaved, and one atom gets on electron and the other

does not get any.

y Reactions ofHalogenoalkaneso Substitution

Happens when KOH/NaOH is dissolved in H2O Also, dilute KOH and NaOH

oElimination

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.

y Frequentlyasked bondangleso FBF

120oo NHN

107oo HOH

104.5oy Molecules withH-Bonding

o Molecules with N-H bonds, such as NH3o Molecules with O-H bonds, such as H2O and C2H5OH

Both happen

under reflux.


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Bu

do

en bondin

in 2

is s

on

e

han in Ethanol because the

h

do

en bondin

is limited b

the factthatthee is onl

one h

do

en in

each ethanol molecule

ith sufficient + cha

e

he eas in

ate the ea e 2 h

d o

en

ith + cha

e thus allo

in

mo e bonds to be fo med

o Molecules ith H-F, such asF

TheMaxwell-Boltzmanndistributiondiagram

y Iodineand Sodium Thio-sulphatetitrationso The indicato

used to find the end point ofthe titration is Starch.

y Balancing Ionic Equations and erall Equationso

When doin

this, onl

certain particles can be added Electrons (e-) WaterMolecules (H2O) Protons, or

dro

en ions (H+)

When balancin alaline reactions,OH

-ions can be added

o You first have to balance the electrons, b! multipl! in" one side b! two differentinte

"

ers

o Then cancel the # + ions and # 2$ on both sideso Then the equations should be balanced

y The boilingpointofsubstanceso It all depends on the intermolecular forceso In a question,when the onl% variable is the chain& len' th,then the lon' est un&

branched chain will have the hi'

hest boilin'

point.

o Ifthere is a functional ( roup, such as ) 0 ,then this will be the choice, as normall1 inorganic molecules without special functional groups,there are onl

1

London forces.

But in alcohols,there are also dipole forces.

500o2

Fewer moleculeswill have the activation

energy, because there is less 3 inetic

energy due to a lowertemperature.

At lowero2,the

curve

will shif

tto

the right.


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o Atypical e4 ample5

The correct answer is D. Because it has 6

7and also,the alcohol is primary. In secondary alcohols,

the 6

7is cluttered by hydrogen atoms,thus the intermolecular bonding is less effectthan in D.

Unit 3

y EnthalpyChangereactions (E 8 EXCEL_JUN_09_3B_2)o If, in a reaction, a metal is involved, often the mass ofthe metal is notta 9 en into

considerationwhen measuringthe enthalpy change, because the specificheat

capacityofthe metalis negligible.

o The reasonwhythe e@ periment is continuously stirred is to spreadoutthetemperature more uniformly, also to ma A e sure that all the reactants havereacted.

o The greaterthe enthalpy change,the greaterthe difference in reactivity betweenthe reactants(c).

y Thewaytodistinguishhalides using sulphuricacid o Achloride, such as Lithium B hloridewould give outwhite/steamy fumes.o Abromide, such as Sodium Bromidewould give outbrown/orange vapour or liquid.o An Iodide, such as Potassium Iodide would give apurple vapour / dark solid or liquid

or residue.


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Physics

UnitC

y The point beyond the elastic limit is called the yieldpoint, here there is a large increase instrain for a small increase in stress, meaningthat for a small force there is a large e

D

tension.

Figure 1: Properties ofMaterials Stress-Straingraph

y Streamlined flow or laminar flow is flowthat has noabruptchange in direction or speed oflow, usuallythis occurs at low speeds.Streamlines donot mix.

y Turbulent flow is flow inwhich there is abruptchange in speed and direction and thuscauses the formation ofeddies.

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Comment [R1]: In fluid dynamics , an eddy is

swirling of a fluid and the reverse current created

when the fluid flows past an obstacle.


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y The major difference between ductileand malleable is thattheforces ofattractioninmalleable materials areweak 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.

y Tough materials are those thatabsorb alotofenergybefore brea E ing. Buthard materials cannot,they cannot

absorb energy much, butthey can withstandlargeimpactforces, i.e.they are hard to scratch or indent.

y Astrong material is a material thatrequires a large stressto brea F it.

y A hard material is a materialwith high breaGing stress,

meaningthat a lot of energy is required to brea G it.

y Compressive strain H

y Compressive Stress I

Figure2: PH01_0906_14-15_Worked

y Often, a data logger is used, because it can accuratelyrecord large amounts of data in realtime, so it is easierto process, and reduces the chances of human error.

UnitP

y A source of light emits a train of waves lasting 0.04 s. The light has a wavelength of600 nm and the speed of light is 310

8ms

-1. How many complete waves are sent

out?

A. 2.0 107B. 4.5 107C. 2.0 1010D. 4.5 1010

o We need to Q eep in mind the values of and n,=10R 6 and n=10S 9o The total length forthe ray of light is o


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o The single resistorwill have 2X the current.o Therefore, as P=I2R, currentwill be made fourtimes, and therefore quadrupled. o T

his is inco

mparisont

oone

ofthetw

oresist

ors, n

ot b

oth

ofthem.

o Thus,the firstwill have 4 times than one atthe 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 10-4JB. 0.144 JC. 144 JD. 9000 J

y Rememberthat

y NTCresistors decrease theirresistance as the temperature increasesy As the voltage increases, so does the temperature ofthe NTCresistor y As we can see thatthe curve becomes steeper, so for a larger value ofV,there is a greater

increase In I than R,which is the gradient

y Thus, theansweris B.Because

y Another interesting question is Question 8_SAM_GCE_UNIT2


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y

y So, y This as

,

y The rate atwhich electrons are liberated due to the photoelectric effect, from a metalsurface is depends on the distance between the source of light and the metal surface.Thus,

thenumberofphotoelectrons emittedonlydepends ontheintensity, notthefrequency.

y UV light onlytransfers energyto the metal surface , not electrons, so on a positively chargedmetal surface, on an electroscope, itwould have no effect.

yy The difference between sound waves and radio waves T

Radio Waves Soundwaves

1. Transverse2. Travels through Vacuum3. Much fasterthan sound4. Infinite range of frequencies

1. Longitudinal2. Travels through medium3. Much slowerthan radio4. Frequencies between 20 U z V 20K U z


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y The higherthe frequency,the lowerthe wavelength, because all electromagnetic waveshave a speed of .

y As , i.e.

This question is ta W en from EdeX

cel June

2009 Physics paper2. Section A question 2.


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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 notthe answer because the actual reading is to one decimal place as well. It is notA, because

the students recordings are very close to each other, and therefore we may presume that he

Y

she hasmade very few mista es.Thus leaving B, as the most logical conclusion.


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Business Studies

Techniquey Wheneverreadingthrough a case study ,tryto understand the motives ofthe business, and

evaluate the position from their point of view.

y When answering a contea t in Edea cel,these are the guidelines thatyou have to follow: o Knowledge, most ofthe time,this is a definitiono Applicationo Analysis,this is where you analyse the datao For higher marked questions,there will be an evaluation.

y This is an eb ample ofthe shorterquestions:y Examine oneway in which Innocent Drinks achieved a competitive advantage.SAM 9(b) [6]y Competitive advantage is any feature of a business that allows itto compete effectively. In

this case,the endorsement byCoffee Republic, by stockingtheirgoods .As Coffee Republic is

an established brand, having many stores,this would mean that more people will have achance to try outthe product, so itwould raise consumer awareness.Furthermore, as a

brand has endorsed ID,that in itself is an as now a brand image is attached to their name.

Answering MCQs in both Unit 1 and Unit 2

From Edexcel Business Studies June 2009 Unit 2

6. Chocolate maker Green & Blacks objective is to increase profit.

(a)Which one of the following is most likely to be the best tactic? [1]

(b)Explain why your answer is correct? [3]

y The first markwould be a mark forknowledge, so the definition of eithertactic or profitwould be acceptable, as they are keyterms in the question. So,thus would be the

knowledge mark

y The second markwould be an explanation as to whyyou chose D,thus showingyourunderstanding, a third mark could also be scored out ofthis

yHowever, easierway ofgetting a mark is to explain whythe other options are wrong, so forexample whywould ceasing advertising be the wrongthingto do.

y But,there is a fundamental markforwhyyou choseyouroption.The othertwo marks areoptional marks,they can be gained from further explainingyour choice orthe application of

yourknowledge

Comment [R2]: Knowledge.Here we have

defined whatCompetitive advantage means.

Comment [R3]: Application ofyourknowledg

Comment [R4]: Analysis1 ,the advantages of

havingCoffee Republic help you out.

Comment [R5]: Analysis2

Comment [R6]: Keyterm

Comment [R7]: Keyterm


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Unit 1

y Competitiveadvantage: 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.

y Also, in Dave Hall defined as an advantage which allows the business to perform better thanits rivals.

y The difference betweenc

nique 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.

y Usually the term USP is referred to niche markets and Competitive advantage to massmarkets.


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Sd

Coding

y Meano Affected byall,to calculate the actual mean, just equate it backthrough the coding

y StandardDeviationo Just affected bydivisionand multiplicationo Just multiply it bythe factoryou divided by, and vice versa

y Product momentcorrelationo Not affected

y o This is affected byall, just equate a and b backthrough the equation

y Varianceo Affected bywhatyou have multiplied it by, and nothing else.o IfVar(a+bx)o Then the answerwould be b

M1

Vectors

y When something is due south or due north of a point.

y Whenever calculatingthe acceleration in Chapter 3 question, always calculate them fortheentire body at all times.

C3

Trigonometric Identities

58753902 important points physics chemistry and mathematics

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