I did a lab the other day where we separated a mixture of NaCl, SiO2, and CaCO3. The Mixture was made by my professor and we did not know the original amounts of each compound. After recovering all of the compounds we found that there was..
36.4% NaCl
36.4% SiO2
40.9% CaCO3
the total % recovered was 113.7% with a 13.7% error. I do not understand how we recovered more that the original sample. One of the post lab questions ask
1. List possible manipulation errors that might contribute to the following errors:
-obtaining a significant larger amount of NaCl than as present in the original sample;
-Obtaining a significant small amount SiO2 than was present in the original sample.
help me please! I thought maybe the physical form of the NaCl changed the mass after the boiling off process, I have also thought about the chemical bonding process, but it doesn't make an sense to me.
duplicate
When conducting a lab experiment, it is common to encounter errors that can contribute to discrepancies between the expected and actual results. In your case, where you recovered more than the original sample, the errors may be attributed to various factors. Here are some possible manipulation errors that could have led to the percentage discrepancies you observed:
1. Contamination: It is possible that some external contaminants were introduced during the separation process, thereby increasing the measured mass of one or more components. Contamination can occur from sources such as improper handling, impure equipment, or environmental factors.
2. Incomplete separation: The separation technique employed might not have been entirely effective in segregating the components. For example, if the separation process for SiO2 was not thorough, it could result in a lower recovered mass compared to the original sample.
3. Measurement errors: Mistakes in taking measurements can also contribute to errors. This includes inaccuracies in weighing, transferring, or recording data during the experiment. These errors can accumulate and affect the calculated percentages.
4. Loss during transfer: There might have been losses during the transfer of the components from one container to another, leading to an underestimation of the recovered mass. For example, some of the SiO2 might have been left behind on the filter paper during filtration.
Regarding your specific questions about NaCl and SiO2, the physical form of the compounds and chemical bonding processes are unlikely to have a significant impact on the mass measurements. The mass of a substance typically remains constant during physical and chemical changes unless there is a reaction or loss.
To troubleshoot and identify the specific source of the errors, you can consider the following steps:
1. Evaluate your separation techniques: Review the separation procedure used for each component and assess if any steps could have been improved or if any shortcomings might have occurred.
2. Repeat the experiment: Conduct the experiment again, ensuring careful attention to the separation process and minimizing potential sources of errors. Compare the results obtained from repeated trials to identify any consistent discrepancies.
3. Validate your measurements: Verify the accuracy of your measuring instruments and techniques by calibrating or cross-checking them against known standards. This will help ascertain if measurement errors played a role in the observed discrepancies.
4. Analyze the data: Scrutinize the data obtained during the experiment, looking for any inconsistencies, anomalous readings, or patterns that could indicate specific sources of error.
By carefully examining the possible manipulation errors and taking corrective measures, you can work towards minimizing the discrepancies in your experimental results and improving the accuracy of your findings.