Hello,
I just finished an experiment in class dealing with the separation of a sand and salt mixture through the means of filtration (with filter paper and water) and evaporation (using a hotplate). As I was calculating the percent recovery, I yielded 103.93% of the recovered mixture. In comparing my measured sample before filtering to my recovered mixture, I also had an extra 0.10 g. Do you have an answer as to why I may have a percent recovery over 100%?
Also, is it possible for there to be minuscule amounts of left over water from evaporating the water from the salt (like 0.10 g for example)? Like could there be impurities from the water that I may have failed to fully dry off? In addition, my filtered paper with the sand, and the flask that evaporated the water from salt had a chance, for these last four days, to evaporate more, so would the water be completely dried off by now, or there is still water that has not been evaporated? Finally, could external contaminants have altered the mass and made the mass of the recovered mixture more than what it originally weighed?
I can not conceive a thorough idea on what else I could have done wrong and I would like to have an extra opinion on my experimental uncertainty.
Thank You!
Hello,
It seems like you have a few questions related to the percent recovery and the extra mass you observed in your experiment. Let's break it down:
1. Percent Recovery over 100%: Percent recovery is calculated by taking the mass of the recovered mixture divided by the initial mass of the sample, multiplied by 100. Percentages over 100% typically indicate that there was an error in measurement or calculation. In this case, it is possible that there was an error in measuring the initial mass of the sample or in the mass of the recovered mixture. Double-check your measurements and calculations to identify any potential sources of error.
2. Minuscule amounts of leftover water: It is unlikely that you would have leftover water of 0.10g after complete evaporation. However, it is possible for impurities to remain, which could contribute to the extra mass. To ensure complete evaporation, you can continue heating the mixture until there is no visible moisture or until the mass remains constant over a period of time.
3. Drying of the filtered paper and flask: If your filtered paper and flask were left uncovered for four days, it is possible that they may have absorbed atmospheric moisture during that time. This could potentially contribute to the extra mass observed. To minimize this, it is important to cover or seal the filtered paper and flask once they are dry to prevent any moisture absorption.
4. External contaminants: Yes, it is possible for external contaminants to alter the mass and contribute to a higher mass of the recovered mixture. It is important to ensure a clean experimental environment and handle the materials with care to minimize the introduction of any foreign substances.
To address experimental uncertainties, it is crucial to repeat the experimental process multiple times to ensure consistency and identify any sources of error. Carefully review your procedures, measurements, and calculations to identify any potential areas for improvement.
I hope this helps! Let me know if you have any further questions.