PAG 1.2 determination of the relative atomic mass of magnesium

Question 1

method 1

Answer 1

1) upside down measuring cylinder in tub of water
2) add 10 cm3 of 1.00. mol dm-3 aq sulphuric acid to the conical flask
3) weigh accurately 0.12 g of magnesium
4) remove the stopper, add magnesium to the flask and quickly replace the stopper
5) collect the gas and record the final volume of hydrogen

Question 2

method 2

Answer 2

1) add 10 cm3 of 025 mol dm-3 aq sulfuric acid to the conical flask
2) weigh 0.20 g of magnesium oxide
3) add the magnesium oxide to the aq sulfuric acid a spatula at a time with swirling for one minute into all of the solid has been added
4) gently heat the conical flask without allowing it to over-heat
5) weigh a basin
6) filter the contents of the conical flask into the basic and wash the filter paper and remaining solid with distilled water into the basin
7) gently heat the solution of magnesium sulfate and stop when crystals start to form
8) allow remaining liquid to evaporate naturally

Question 3

give two possible errors in this experiment

Answer 3

some hydrogen gas may have escaped before the bung was put back in
some magnesium may not have reacted