Chemistry Paper 6 (Igcse) -Tips
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 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 the 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 burning of the substance.
11) explain the term (decant).
Filter/Pour the liquid leaving the solid alone.
12) Why is concentrated sulphuric acid not used to dry ammonia? Because it will 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
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 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 the 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 burning of the substance.
11) explain the term (decant).
Filter/Pour the liquid leaving the solid alone.
12) Why is concentrated sulphuric acid not used to dry ammonia? Because it will 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