Hi first off you made a mistake in your calculation. That is very obvious because you can't have 1200% of something that would be like saying I have 5 grams of fertiliser but 6000 grams of sulphate in that fertiliser. There is no way you can have more than 100 percent. it violates logic as well as conservation of mass law.
Okay now to where u made that specific mistake look at your step where you said you found 4.00 grams of barium sulphate.
However, when you calculated moles you put n = m/MM with m = 100 it should be m = 4.00
Which would end up changing your final answer it should be around 48.43% (reasons why this may be higher discussed below)
Now if I was marking your discussion you wouldn't get a good mark for it.
You have only said things very brief without actually explaining anything in detail. You haven't addressed the three main areas every science report should be based on: validity, accuracy and reliability. You cannot assume that the reason why your value is high is just because the mass of the sulphate is higher than what is advertised (this is highly unlikely since it is a commercial product). Other reasons are much more likely. Also, your language you use isn't how you should write a scientific report. You should try to limit use of words like my and I etc. example below
Structure your conclusion/discussion like this:
- Comment on accuracy of result to actual value (the sulphate content of the fertiliser sample was determined to be 48.43%. This value is significantly higher than the 17% value expected to be obtained for the fertiliser.)
- Then discuss reasons why your answer was off. This can include:
- The barium sulphate precipitate was not fully dried --> the implication of this is that some of the mass you measure for 4.00 g of barium sulphate is actually probably water. So your actual mass of barium sulphate will be lower.
- The experiment assumes that the only precipitate that formed was is barium sulphate. You need to remember that fertiliser is a mixture. It contains things like phosphate --> this is also something that forms a precipitate with barium (show equation for this in your report). Therefore, once again the mass you measured may have had barium phosphate in it (lowers actual mass of barium sulphate you had)
Okay so those are the main errors that arise usually in accuracy for this experiment. But you still need to talk about how to address those issues and improve other parts of accuracy:
- Dry the precipitate in an oven to remove the water from it
- To improve accuracy we can also increase the amount of decimal places on our measuring scales
Reliability:
- you only did the experiment once. Therefore it is not reliable. You should mention this. and say you can improve the reliability of the experiment by repeating the experiment 2 more times at least
Comment on validity
Conclude
