PAG 1.3 determination of the formula for magnesium oxide

Question 1

method

Answer 1

1) measure the mass of the crucible and lid
2) put the magnesium ribbon into the crucible and reweigh it with the lid
3) put the crucible on a pipe-clay triangle
4) raise the crucible lid using tongs to control the reaction
5) when the reaction is nearly complete, place the crucible lid on the side and heat the crucible strongly for 5 mins while tapping the magnesium oxide gently with tongs to break up the residue
5) allow crucible to cool and reweigh crucible

Question 2

why did you need to raise the crucible lid slightly when you first heated the magnesium?

Answer 2

to allow sufficient oxygen to enter the crucible

Question 3

what was the purpose of breaking up the magnesium oxide whilst heating the contents of the crucible strongly for 5 mins?

Answer 3

to ensure it could fully react with the oxygen available

Question 4

the formula from this experiment often shows slightly less oxygen than is present in pure magnesium oxide. suggest why.

Answer 4

not all magnesium may have reacted

Question 5

why does magnesium react with oxygen instead of nitrogen?

Answer 5

oxygen is more reactive than nitrogen