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Uʟᴛɪᴍᴀᴛᴇ IGCSE Nᴏᴛᴇs ﹐ E﹣Bᴏᴏᴋs ᴀɴᴅ Rᴇsᴏᴜʀᴄᴇs ᴴᴰ

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physics paper 62 was completely new
no... mostly all topics asked were same as last year's plus it was quite easy
hey sohaib672002 wat werer the two differences between the images on yesterday"s physics paper62
evry1 has that same confusion .... i wrote one was diminished and the other magnified. i kno both r almost same but there was nuthin else i cud think of.
does sum1 hav tips and important info for chemistry paper62 like the one for physics? that was quite helpful thnx :)
 
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Hey everyone,I have a quick question regarding the article in ESL.So I wrote an introduction(includes topic and my opinion),2 main paragraphs with 1 advantage in each,and a conclusion with all whats needed...So basically i was in favour of the idea.Should I have mentioned 1 adv and 1 disadvantage?or is what I did just fine?Thanks!
 
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Hey everyone,I have a quick question regarding the article in ESL.So I wrote an introduction(includes topic and my opinion),2 main paragraphs with 1 advantage in each,and a conclusion with all whats needed...So basically i was in favour of the idea.Should I have mentioned 1 adv and 1 disadvantage?or is what I did just fine?Thanks!
U should have anyways u cant do anything so Just relax!
 
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hey dude
do u have some notes for chemistry p6
thanks
السلام عليكم و رحمة الله و بركاتة

This is for IGCSE Chemistry
In this thread I have uploaded some Resources you can use while studying,I hope this little helps you and makes you get straight A*

I Wrote the guide for Paper 6 and the rest I collected and kept it here for you all

I wish you all the best and all I ask is Pray for me

All Past papers are in ONE folder only, uploaded on 4shared.com

Download them all in One click Here(y)

And this Amazing Study Guide

Link:
http://www.4shared.com/office/PAJMBUf1/IGCSE_Chemistry_Study_Guide.html

If you know anyone who needs help please refer them to this page

Are you an AS level Chemistry student or you know one?
Check out Chemistry for you 2
1) What is the purpose of ice or cold water? To cool down the gas so that it condenses and turns into a liquid.
2) when the gas collecting tube is upside down, give a property of this gas. It is less dense than air.
3) Why is a pencil used in drawing thenorigin line in chromatography? If pen was used, it ill dissolve giving collies and so, the experiment won't be accurate.
4) When using ethanol, give a better apparatus arrangement, and why? Cover apparatus wth a lid, because ethanol is volatile.
5) In the tests and observation tables, when in the first row, they tell you that upon heating condensation occured, there will be a question asking what does this show about the solid? It is hydrated.
6) when copper is used in the test, and the answer is four marks, the best answer is: light blue precipitate (ppt) which is soluble in excess to form dark blue solution.
7) Why is this experiment done in a fume cupboard? It releases harmful gases that are poisonous. It is toxic.
8) Which result appears to be inaccurate? It is the point not appearing on the drawn graph, you read it's x-axis and write it with a reason indicating that it doesn't occur in the graph.
9) Why should the solid be crushed? It increases surface area for a faster rate of reaction.
10) Why is the experiment made in a well-ventilated room? To prevent the burning of the substance.
11) explain the term (decant). Filter/Pour the liquid leaving the solid alone.
12) Why is concentrated sulpharic acid not used to dry ammonia? Because itnwill reach the base ammonia, which is neutralization reaction.
13) Why should samples be taken from different parts of the field? To get more accurate results.
14) Suggest why it is important to know the pH of the soil. To see which is the best place for growing, and wht kind of base to use for neutralizing it.
15) What is necessary for rusting? Water (humidity) and oxygen (air).
16) Suggest why in an experiment for rusting the water level increases. Oxygen is used up, and water is used to take its place.
17) For electrolysis, state the observations. The bulb will light - A metal is formed on the cathode - Fizz of gases produced.
18) Suggest a suitable material for electrodes. Graphite - Carbon - Steel.
19) when copper oxide is reacted with hydrogen, what is the colour change? Black to brown, because copper oxide is reduced to copper.
20) How can you distinguish between water and ethanol? Use cobalt chloride paper, it turns from pink to blue with water, but there will be no change with ethanol.
21) how can you distinguish between sulpharic acid and aqueous sodium sulphate? There are three tests, you can use a metal carbonate in which carbon dioxide will be produced with sulpharic acid but there'd will be no change with sodium sulphate. You can add a metal, in which hydrogen is produced with sulpharic acid, but no change in sodium sulphate. Finally, you could use an indicator like litmus paper, it will change to red with sulpharic acid, but there will be no change with sodium sulphate..
22) how can you distinguish between hydrochloric acid and nitric acid? Add silver nitrate, in which white ppt will be formed with hydrochloric acid, but there will be no reaction with nitric acid.
23) What is the purpose of the mineral wool? To absorb and hold the liquid.
24) When there is a delivery tube involved in a question, what precaution should be taken in the experiment when the heat is removed? Remove the delivery tube from water to prevent suck-back.
25) In rate of reactions, always include the word "collisions between particles".
26) How can you distinguish between aliens and alkane? Use bromine water, in which the alkene will decolourise it to colorless, but nothing happens with an alkane,
27) how can you distinguish between chlorine and sodium chloride? Add litmus paper, it will bleach with chlorine, but nothing happens to it with sodium chloride.
28) How can you distinguish between copper sulphate and copper carbonate? Acidify with hydrochloric acid, and add barium chloride, there will be white ppt with sulphate, but no white ppt with carbonate. OR just add hydrochloric acid, in which nothing happens with sulphate, but a fizz or effervescence of carbon dioxide will occur with carbonate.
29) When a measuring cylinder is used, and they ask for a change in apparatus to get more reliable results, you should say that a biuret can be used instead as it is more accurate.
30) volume of reagent used decreases if it is more concentrated.
31) in an experiment observation of pH value, and they ask what type of acid/base is used, your answer should be weather weak or strong. A strong acid lies between pH values of 0 and 2, and a weak one lies between 3 and 6. 7 is neutral. A weak base lies between 8 and 11, while a strong one lies between 12 and 14.
32) A concentrated acid is an acid that contains a large number of H+, hydrogen ions. Vice versa with dilute acid.
33) A concentrated base is a base that contains a large number of OH-' hydroxide ions. Vice versa with dilute base.
34) a strong acid is one that ionizes completely giving H+ in solutions. Vice versa with a weak one..
35) A strong base is one that ionizes completely giving OH- in solutions. Vice versa with a weak one..
36) Concentrated: is a solution that contains a large number of solute or little amount of water is involved.
37) How can you make crystals? 1)heat till point of crystallization. 2) leave to cool gradually. 3) filter, dry and collect the crystals!
38) How can you detect the point of crystallization? Place a stirring rod in the solution and see the formation of the first crystals on it.
39) When you crush, you use a pestle and mortar.
40) Grass is ground with ethanol rather than water because clorophyll is more soluble in ethanol.
41) Colour of rusty iron fillings is brown (orange and red are I think accepted)
42) If pure oxygen was used instead of air, rusting will be faster.
43) you can speed up the drying process by using a fan or by increasing temperature or by using a hair-drier if you have one ) , NOT a catalyst.
44) The action of a lie big condenser is to change steam to water.
45) to check for the purity for a collected solvent, test it's melting or boiling point.
46) The chromatogram needs to be sprayed with locating agent is amino acids are investigated because they are colorless.
47) If water contained salt, this will have no effect on rusting, however if a bigger substance is being rusted, it will be slower.
48) Hydrated copper sulphate will turn from blue to white upon heating.
49) saturated: no mo solute can be dissolved in a solvent AT A CONSTANT TEMPERATURE..
50) An excess amount of reactant is used to make sure all the other reactant will be used.
51) Sometimes, crystals are dried using filter paper instead of heating to prevent the complete loss of water from crystals, and to prevent crystals from breaking.
52) how could you know which reactant is in excess? At the end of the reaction, the excess reactant will be visible.
53) excess means more than what is needed.
54) when lead bromide is used, you can use a fume cupboard or use goggles,lab coat,gloves,,, because it is toxic.
55) to separate two different solutions with different boiling point, use fractional distillation.
56) Physical test of water: heat, it will boil at 100 degrees Celsius, or heat ice and it will melt at 0 degrees Celsius.
57) chemical test of water: Add blue cobalt chloride paper, it turns pink OR add anhydrous copper sulphate, it turns blue.
58) fire will be produced if alcohol is touched with lighted splint, therefore a water bath should be used when heating it. Lagging or cloth can be used to control temperature for accurate results.
59) unreacted reactant is called excess.
60) As reactants are heated, the particles gain energy, move faster, and their kinetic energy increases therefore there will be more collisions and rate increases.

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Areeb Mohsin
Notes To Study For Chemistry Paper 6

Topics

-Salt Preperation

-Filteration, distillation, Dissolving, Chromotography.. fractional distaillation.. filtration.. precipitation

-Salt Analysis ( Cations and anion tests)

-Testing for Ions

http://www.absorblearning.com/chemistry/demo/units/LR1106.html

-Labelling of apparatus

-Rate of reaction.

-Graph drawing and explaining curves etc..

-Test for gasses

-Fermentation

-Basic knowledge of electrolysis (VERY BASIC)







Salt Preperation-

To Prepare Soluble Salts:

1- Add the acid in a beaker then add a solid (base/carbonate/metal)

2- Then solid is in excess so the salt is formed in a solution

3- Filter off the excess solid using a funnel

4- Put it in an evaporation dish, evaporate it to reduce the volume of the solution.

5- Transfer the hot liquid to a dish and crystals are formed after leaving it to cool and until the solution is saturated.

To Prepare insoluble salt:

1- Add a soluble salt solution (acid +(base/carbonate/metal)) with another soluble salt solution. An insoluble salt is formed as a solid

2- Filter it using a funnel to collect the salt.

3- The salt that stays on the filter paper is taken and is washed with a cold water and left to dry to form insoluble salt.






Salt Preperation- If it is Soluble or Insoluble

For soluble

Use titration...ex:NaCl(use NaOH and HCl) place either one in a burette and the other in a beaker add universal indicator, then start adding drops of solution in burette until it goes green...note the volume used, repeat using same volumes but without indicator, then apply crystalisation OR evaporation

For Insoluble

Use precipitation or nuetralisation...( Use preciptation only when the cation is above Hydrogen in the reactivity series) ex: CuCl2 u cannot use precepitation cause Cu is below Hydrogen so u use nuetralisation where u react base (CuOH or CuCO3 or Cu(OH)2) with EXCESS HCl to from CuCl2 +water....u then filter and dry between two sheets

3)precpitaion is basically same procedure as nuetralisation, u just use a metal higher than hydrogen instead of the base...








There are two types of salts that can be prepared ... Insoluble and the other ones are soluble .

There are different methods such as ..

For preparing soluble salts - Titration method

1. Put 25cm cube of base eg NaOH soln into a flask using a pipette an then add 2 drops of phenolphthalein indicator which turns pink when added .

2. Add an acid eg HCl from a burette little at a time ( Mark the starting point ) .. And mix it carefully by swirling the flask which helps in mixing of acid and the base .

3. By adding the acid more dr by drop would result in to the solution getting colourless which means that all the acid is used up and the solution is neutral ( Mark the ending point ) . By this you can say that how much acid is needed to neutralise 25cm cube of base .

4. Then , again .. Carry out this reaction WITHOUT the indicator ( this is because the indicator would make the salt impure ) . Put 25 cm cube of base into a flask and burette the same amount of acid into it .

5. Then .. Heat the solution from the flask and evaporate the water .. You'll notice that White crystals of NaCl will be left behind !




Making insoluble salts with metals which depends upon the metals like eg mg al zn and fe can react properly with the acid .. Na K and Ca won't react bcz they are too violent .. Lead reacts slowly whereas cu ag au do not react with the acid !

In this reaction let's use dilute h2so4 as an acid and zn in solid form to form znso4 as an soluble salt .

1. Add zn to the acid in a beaker . As it starts to dissolve in the acid .. It releases hydrogen bubbles . This bubbling stops when the acid is used up .

2. Some zinc is still left as the metal was in excess .. So .. Remove it by filtering which leaves an aqueous solution of zinc sulphate .

3. Heat the solution to evaporate some of the water and then leave it to get cool .. The crystals on znso4 soon start to form !

Preparation of Soluble salts from insoluble base and an acid ( neutralisation )

Copper will not react with dilute h2so4 .. So to make a copper salt , you must start with a base like copper(2)oxide which is insoluble and .. Blue cuso4 forms with h2o .

1. Add copper(2)oxide to dilute h2so4 . It dissolves on heating and turn the solution to blue . Keep it excess until no more of it is dissolved .. Which will mean that no more acid is left to be used up !

2. Remove the excess solid by filtering which leaves up a blue solution of copper(2)sulphate in aqueous state .

3. Heat the solution to evaporate some of the water .. And then leave it to be get cooled . blue crystals of copper (2) sulphate start to form !

Preparation of insoluble salts .

Theres only one way given in our syllabus to prepare them . Which is by precipitation .

Eg barium sulphate is an insoluble salt which can be prepared by adding barium chloride and magnesium sulphate .

1. Make up solutions of barium chloride and magnesium sulphate .

2. Mix them . A White precipitate of barium sulphate forms at once .

3. Filter the mixture .the precipitate is trapped in the filter paper .

4. Rinse the precipitate by running distiller water through it .

5. Then place it in a warm oven to dry .

Keep in mind that - to precipitate an insoluble salt , you must mix a solution that contains it's positive ions with the one that contains it's negative ions

Like in this experiment ..

BaCl2 - Ba2+ and Cl-

MgSO4 - Mg2+ and SO4 2-




Summary of above notes

For soluble salt, you may use a solid base (or metal) and an acid, OR a soluble base (alkali) and an acid..

For an insoluble salt, you use the titration method.

So therefore, we have three types of experiments we need to learn:

1) Solid base (or metal) and an acid to make a SOLUBLE salt.

2) Soluble base (alkali) and an acid to make a SOLUBLE salt.

3) Precipitation method to make an INSOLUBLE salt.

Here are the steps you need to learn for each experiment, and you should be able to recognize from the reactants they give you which method you need to talk about, because if you misread the question, and write another method, all your answer will be wrong...

1) - Add excess metal (metal oxide or metal carbonate.. Etc) (for example zinc) to acid (for example sulpharic acid) in which zinc sulphate and hydrogen gas will be formed. Excess solid settles down.

- As the gas (hydrogen) escapes, filter the mixture to remove the excess solid.

- Collect the filtrate ( aqueous zinc sulphate solution).

- Heat to evaporate water to collect salt.

2) - I will use sodium hydroxide as an example for alkali, and sulpharic acid as an example for acid.

- Transfer sulpharic acid from a biuret gradually into a flask containing an alkali (Sodium hydroxide) and universal indicator.

- as the colour of the solution changes, stop adding the acid in which neutralization has been reached. This method is called TITRATION!

- Repeat the experiment using same volumes of acid and alkali but without indicator.

- Heat the solution (sodium sulphate) to evaporate water and collect the salt.

3) - To precipitate an insoluble salt, you should mix a solution containing it's positive ion with another solution that contains it's negative ion.

- Add the correct solutions.

- Filture the mixture ( the residue will be the insoluble salt).

- Wash he residue to purify it.

- Leave the residue to dry then collect.

Last but not least, sometimes they ask you for crystals, so you writ the appropriate meod above followed by:

- Heat the solution till point of crystallization which can be figures by placing a glass rod in the beaker and observe the formation of the first crystals on it.

- leave the solution to cool gradually.

- Filter, dry and collect the crystals!
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Some general ideas for Paper 6.

· You should know the basic lab apparatus.
· You should know how to read from the burette/pippette/measuring cylinder images given
· You should know to draw a graph
· You should know the identification of ions (test to check the presense of iron(ii) etc)
· You should know Titration
· You should know Chomatography
· You should know Crystallization
· You should know difference between distillation and fractional distillation
· You should know the basic filtration methods
· You should know effect of heat and concentration on reaction

If anyone has any more points, feel free to add to the list
 
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