PAG 1.3 Determination Of Formula

Question 1

What are the first steps in order to determine the formula of magnesium oxide

Answer 1

1) measure the mass of the crucible and lid
2) Put the magnesium ribbon in the crucible then reweigh it with its lid.
3) Place the crucible on top of a tripod with a clay pipe triangle.
4) raise the crucible lid slightly using tongs to control the reaction.

Question 2

What are the last steps of the practical

Answer 2

4) when the reaction is nearly complete, place the crucible lid on the heat proof mat and heat the crucible strongly for 5 minutes. During this time, you should tap the magnesium oxide gently with tongs to break the residue.
5) allow the crucible to cool and reweigh the crucible its contents and the lid.

Question 3

How do you analyse the results

Answer 3

1) calculated the mass of magnesium reacted and then the magnesium oxide formed and therefore oxygen that reacted.
2) Use the masses to work out the moles of magnesium and oxygen
3) Determine the empirical formula of magnesium oxide

Question 4

What is a common mistake for the practical

Answer 4

A common mistake is that yogurt can tap the crucible too hard resulting in it cracking.

Question 5

What are some health and safety precautions

Answer 5

.Wear eye protection at all times
. Don’t touch any apparatus that are hot
. Do not look at any bright light given off when magnesium is heater
. Do not place magnesium ribbon directly into Bunsen flame.