Chemistry Paper 6 (Igcse) -Tips

1445 Words Apr 20th, 2013 6 Pages
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 the origin line in chromatography? If pen was used, it will dissolve giving colours and so, the experiment won't be accurate. Pencil doesn’t interfere with the results.

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
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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