i dont know what type of experiement you are doing but below is what I think. this was from my AS coursework, i hope it helps!!
There were a few errors observed whilst doing the experiment. It was found that when pouring the diluted alkali solution into the volumetric flask, some residue of calcium hydroxide was left. This was washed with distilled water into the flask but as soon as the flask reached the meniscus line, no more could have been poured in; thus leaving some residue in the beaker. This would have had an effect on the accuracy, validity and reliability of the results.
When weighing the powder, there were some fluctuations with the mass of the powder which could not be prevented as there were many factors which could have affected it. This was a limitation as the weighing scale was not as accurate as possible. In addition, the accuracy of the results were fairly good. Most of the equipments used were of high standard to ensure the best valid results. The weighing scale measured up to 2 decimal places; the meniscus line on the pipette could be visibly seen so that when the solution touched the bottom of it, then the solution would be transferred. Also, there was a drop pipette to ensure come accuracy so as to not exceed the required amount of HCL put in the burette.