Our class did an expeiment of adding sodium carbonate and calcium chloride. The experiment only yielded 28% of the calculated yield. The class did the experiment as a group (there are only 4 students in our class) and the experiment was closely supervised by our teacher to ensure accuracy. Why was there so much descepency when everthing was done correctly?
Probably you will never know what but someone (or everyone) did something wrong. CaCO3 is soluble in acids; did the group use DI or distilled water? Did you filter? If so, are you sure the paper caught all of the ppt? Was this 28% the average of all four students or did everyone get 28%. How good were the reagents? Na2CO3 is not absolutely 100%; you never know how much of it is the decahydrate and how much is the monohydrate (or did you calculate the 28% yield based on thinking you used the decahydrate and you really did not? Finally, CaCl2 is a drying agent and absorbs water from the atmosphere. You can't weigh an amount of CaCl2 and know that's pure. It will always contain some water.
There can be several reasons why the experiment yielded only 28% of the calculated yield, even when everything was done correctly. Here are a few possible explanations:
1. Measurement errors: Accurate measurement of the reactants is crucial in determining the expected yield. It's possible that there were errors while measuring the sodium carbonate or calcium chloride, leading to inaccurate quantities of the reactants.
To check for measurement errors, make sure that proper measuring instruments, such as a balance or graduated cylinders, are used. Double-check the measurements before adding the reactants to minimize errors.
2. Reaction conditions: Reaction conditions, such as temperature, time, and mixing, can greatly influence the reaction yield. If the reaction conditions were not maintained consistently throughout the experiment, it could result in a lower yield.
Ensure that the experimental conditions, such as temperature and reaction time, are maintained as per the instructions. Also, make sure that the reaction mixture is thoroughly mixed to ensure proper contact between the reactants.
3. Impurities: Impurities in the reactants or the experimental setup can interfere with the reaction and affect the yield. These impurities can be present in the chemicals used or introduced during the experiment, even unintentionally.
To minimize impurities, use high-quality chemicals and clean glassware. Make sure to wash and dry the glassware properly before conducting the experiment.
4. Incomplete reactions: In some cases, the reactants may not fully convert into the desired product due to various factors, such as side reactions or incomplete reaction conditions. This can result in a lower yield than expected.
To ensure a complete reaction, check if the reaction conditions, such as concentration and ratio of reactants, are optimized. Consider repeating the experiment with slight modifications to improve the yield.
It's important to note that experimental results can vary due to several factors, and it's not uncommon to experience some discrepancy between the expected and actual yield. Through careful analysis of the experiment and addressing the possible reasons mentioned above, you can troubleshoot and improve the yield in future experiments.