Freezing Point of Pure Lauric Acid
Freezing point from trial 1: 43.8 °C
Freezing point from trial 2: 42.9 °C
Average freezing point: ________ (calculations)
Graph
The Correct Answer and Explanation is:
Average Freezing Point of Pure Lauric Acid
Freezing Point from Trial 1: 43.8 °C
Freezing Point from Trial 2: 42.9 °C
Average Freezing Point Calculation
Average=Trial 1+Trial 22=43.8+42.92=86.72=43.35 °C\text{Average} = \frac{\text{Trial 1} + \text{Trial 2}}{2} = \frac{43.8 + 42.9}{2} = \frac{86.7}{2} = 43.35\,°C
Answer: 43.35 °C
Explanation
The freezing point of a substance is the temperature at which it changes from a liquid to a solid under standard atmospheric pressure. For pure substances like lauric acid, the freezing point is a characteristic physical property and is used in many laboratory experiments to study thermal behavior and identify unknown substances.
In this case, the freezing point of pure lauric acid was determined by two trials, yielding temperatures of 43.8 °C and 42.9 °C. To find a more reliable estimate, we calculate the average: Average Freezing Point=43.8 °C+42.9 °C2=43.35 °C\text{Average Freezing Point} = \frac{43.8\,°C + 42.9\,°C}{2} = 43.35\,°C
This average accounts for small experimental variations such as instrumental error, cooling rate differences, or minor impurities introduced during the experiment. Averaging helps reduce the effect of these uncertainties and provides a more accurate representation of the true freezing point.
Lauric acid (C₁₂H₂₄O₂) is a saturated fatty acid commonly found in coconut oil and palm kernel oil. It is frequently used in freezing point depression experiments because it has a relatively high freezing point and is solid at room temperature, making it easy to handle and observe during phase changes.
The graph of temperature vs. time in such experiments typically shows a plateau where the temperature remains constant during the phase transition from liquid to solid. This plateau corresponds to the freezing point, as the heat energy is used not to lower temperature but to reorganize the molecular structure into a solid state.
By determining the accurate freezing point of lauric acid, we lay the foundation for further calculations, such as determining the molar mass of unknown solutes through freezing point depression methods.
