The calculation to find the average was
Final Burette Reading 1 + Final Burette Reading 2 + Final Burette Reading 3 = Average
3
22.5 +22.2 + 22.15 = 22.16
3
Carefully we drew 25ml of Ammonium Hydroxide using a glass pipette. The reason we used a glass pipette, was because this is much more equipment then the regular pipette. We then emptied this into a 250ml conical flask on a white tile, and added 3 of drops of litmus indicator.
We carefully poured, sulphuric acid into a Burette, using a funnel and pipette, till it was exactly at 0, to make sure this was at 0; we checked that the meniscus just touched the top of the line, at eye level.
Turning the nozzle slowly on the burette so it was horizontal we allowed the acid to empty into the conical flask with the Ammonia in it, one drop at a time, until the Ammonia solution and Acid, mixed and turned an almost pinkish colour. Recording how much of the Sulphuric Acid was used, we then repeated this 3 times till they were all 0.1cm3 difference between them, we the calculated the average.
We repeated the procedure again, this time without the litmus indicator, adding the average volume of acid, as accurately as possible. The reason we did this, was so that there wasn’t any other chemicals mixed into the solution, when we heated the ammonium sulphate later.
Pouring the solution, into the pre-weighed evaporating basin. It was then heated over a Bunsen burner for a couple of minutes, until half of the liquid had evaporated. While doing this, we watched the solution carefully, but at a safe distance, so we could see if any of the solution spat out, and if it did, we could move the basin quickly, and put it back when it had settled down.
After this we left the remaining solution to evaporate completely over several days.
After several days, we checked our solution, and found that all the liquid had been evaporated, and crystals, were what remained. We measured the crystals, and recorded all the information in the table above.
The reaction that had taken place was:
Ammonium Hydroxide + Sulphuric Acid Ammonium Sulphate
2NH4OH + H2SO4 (NH4)2SO4 + 2H2O
Moles = Mass of Crystals
Mr (NH4)2 SO4
N X 2 = 14 X 2 = 28
H X 8 = 1 X 8 = 8
S X 1 =32.1 X 1 = 32.1
O X 4 = 16 X 4 = 64
132.1
Moles = 2.85 = 0.02157456
132.1
by
shanz224 (student)
