Describe and explain how each of the following experimental errors or variations might affect your results. (a) you failed to dry the reaction flask after washing it with water. (b) you forgot to add the sulfuric acid. (c) you used twice the amount of acetic acid specified in the procedure. (d) you left out the sodium bicarbonate washing step. (e) your theromometer bulb was 1 cm higher than it should have been.
It would have been better if you had told us what experiment this is.
(a) Failing to dry the reaction flask after washing it with water can introduce moisture into the reaction mixture. This can affect the results in several ways. Firstly, if the reaction requires dry conditions, the presence of water may interfere with the reaction or prevent it from occurring altogether. Secondly, the added moisture can affect the concentration of the reactants, as water may dilute the solution. This could lead to a decrease in the reaction rate or alter the final product obtained. Additionally, if the moisture is not taken into account when calculating the yield or any other measurements, it can lead to incorrect values.
To mitigate this error, it is crucial to ensure that the reaction flask is completely dry before commencing the experiment. This can be achieved by techniques such as oven drying, purging with dry gas, or using a desiccant to absorb any remaining moisture.
(b) Forgetting to add the sulfuric acid can have a significant impact on the reaction. In many cases, sulfuric acid acts as a catalyst or plays a critical role in initiating the reaction. Without sulfuric acid, the reaction may not proceed, resulting in the absence of the desired product. This error would render the experiment unsuccessful.
To avoid this error, it is essential to double-check the experimental protocol and make sure all necessary reagents, including sulfuric acid, are added in the correct quantities at the appropriate step.
(c) Using twice the amount of acetic acid specified in the procedure can lead to an excess of reactant being present in the reaction mixture. This will affect the stoichiometry of the reaction, potentially altering the reaction rate, equilibrium, and the final product obtained. The excess acetic acid might not be completely consumed, leading to unreacted quantities of it in the final mixture. This can skew the results and lead to inaccurate calculations of yields and other measurements.
To minimize this error, it is crucial to carefully measure and dispense the correct amounts of reagents as per the experimental procedure. Following the specified quantities ensures the desired stoichiometry of the reaction.
(d) Leaving out the sodium bicarbonate washing step can have implications for the purity of the final product. Sodium bicarbonate is often used to remove acidic impurities from a reaction mixture by neutralizing them. By skipping this step, acidic substances may still be present, potentially contaminating the product or affecting its properties.
To address this error, it is important to carefully follow the experimental procedure and ensure that all required purification steps, such as the sodium bicarbonate wash, are completed.
(e) If the thermometer bulb was positioned 1 cm higher than it should have been, the temperature measurements during the experiment would be inaccurate. This is because the temperature reading on the thermometer depends on the precise placement of the bulb in the reaction mixture. A higher position would result in measuring a lower temperature, as the bulb would be further away from the heated environment. This discrepancy could affect reaction rate calculations, equilibrium determinations, and any other temperature-dependent analysis.
To rectify this error, one should strive to position the thermometer bulb at the correct level as instructed by the experimental protocol. Attention to detail in equipment setup is crucial for accurate temperature measurements.