ACS Domain 10: Laboratory chemistry Welcome to your ACS Domain 10: Laboratory chemistry 1. ACS: Laboratory Chemistry In a titration experiment, a student uses phenolphthalein as an indicator, which changes color at a pH of about 8.3. If titrating a weak acid with a strong base, which of the following would be the best explanation for a titration curve that flattens near the endpoint? The weak acid is only partially ionizing. The base is volatile. The indicator is not suitable for this titration. The buffer region is extended. None 2. ACS: Laboratory Chemistry During distillation, a chemist notices that the temperature on the thermometer reads consistently lower than expected. What is the most likely cause of this discrepancy? The distillation path is too long. There is an air leak in the distillation apparatus. The heat source is insufficient. The thermometer is calibrated incorrectly. None 3. ACS: Laboratory Chemistry Which of the following laboratory errors is most likely to cause a systematic error in a gravimetric analysis experiment? Using an uncalibrated balance. Variability in ambient temperature. Occasional spillage of sample. Inconsistent drying times for precipitate. None 4. ACS: Laboratory Chemistry In a synthesis experiment, a chemist uses a reflux setup. What is the primary purpose of refluxing a reaction mixture? To increase the reaction rate by increasing temperature. To prevent the loss of volatile reactants. To purify the reaction products. To decrease the pressure within the reaction vessel. None 5. ACS: Laboratory Chemistry What is the primary reason for using an ice bath in an exothermic reaction? To increase the concentration of reactants. To control the rate of reaction. To purify the product. To change the reaction pathway. None 6. ACS: Laboratory Chemistry When calibrating a pH meter, why is it important to use more than one standard buffer solution? To check for the linearity of the pH meter. To extend the life of the pH meter. To increase the accuracy of non-standard solutions. To decrease measurement time. None 7. ACS: Laboratory Chemistry In an analytical chemistry lab, why is it important to perform a blank titration? To determine the end point more accurately. To measure the impurities in the reagents. To establish the titration curve baseline. To consume all of the analyte. None 8. ACS: Laboratory Chemistry Which method is most appropriate for separating non-volatile compounds from a volatile solvent? Filtration. Distillation. Sublimation. Rotavapor (rotary evaporation). None 9. ACS: Laboratory Chemistry In a chemical synthesis involving sensitive reagents, what is the primary reason for using an inert atmosphere? To prevent oxidation of the reagents. To increase the reaction temperature. To purify the reagents. To visualize the reaction. None 10. ACS: Laboratory Chemistry What is the advantage of using a microwave reactor in organic synthesis over conventional heating methods? It increases the yield of the reaction. It decreases the reaction time. It allows for a higher reaction temperature. It eliminates the need for solvents. None 1 out of 10 Time is Up! Time's up
