Question

An experimenter is attempting to determine the internal energy of a well-known compound. He cleans his glassware, completes the synthesis, calibrates a bomb calorimeter, and then uses it to measure the appropriate thermodynamic values. Which of the following errors did he make? (A) He did not determine if the compound was novel or if the information has already been determined. (B) He did not have a specific goal at the beginning of his research. (C) He should not be involved in both the synthesis of the compound and later testing. (D) He should have calibrated the calorimeter before the synthesis of the compound.

Short answer

Option D: The experimenter should have calibrated the calorimeter before the synthesis of the compound.

Step-by-step solution

Analyze the Question

Understand that the question is asking you to identify which procedural error the experimenter made while attempting to determine the internal energy of a compound.

Evaluate Each Option

Begin by examining each choice to see if it constitutes a procedural error.

Consider Option A

Option A states that the experimenter did not determine if the compound was novel or if the information had already been determined. This could be a problem if the experiment aimed for novel results, but it is not necessarily a procedural error in measuring internal energy.

Consider Option B

Option B posits that the experimenter did not have a specific goal at the beginning of his research. While having a goal is important for research direction, it is not a direct procedural error in the context of measuring internal energy.

Consider Option C

Option C suggests that the experimenter should not be involved in both the synthesis and testing of the compound. There is no inherent procedural error in this, as one person can competently manage both tasks, especially in a well-controlled experiment.

Consider Option D

Option D states that the experimenter should have calibrated the calorimeter before the synthesis of the compound. Calibration of the calorimeter is crucial for accurate measurement. Failing to do this could lead to errors in the thermodynamic values obtained.

Conclude the Correct Error

Based on the analysis, the procedural error lies in the calibration process timing. Therefore, option D is correct because the experimenter should have calibrated the calorimeter prior to the synthesis to ensure accurate measurements.

Key concepts

Internal Energy Measurement

The internal energy of a compound is a fundamental quantity in thermodynamics that represents the total energy contained within the system. It includes both potential and kinetic energy of all particles within the substance.

When measuring internal energy, scientists often use calorimetry, a method that measures the heat exchanged between a compound and its surroundings. This information allows us to deduce changes in internal energy during chemical reactions.

Accurate measurements require that the system be carefully isolated from the external environment to avoid any heat loss or gain, which can affect the results. Furthermore, it is crucial to ensure that the equipment used, such as a calorimeter, is properly calibrated and maintained to ensure precise readings.

Calorimeter Calibration

Calibration is a critical process in ensuring that your calorimeter provides accurate measurements. A calorimeter is an instrument used to measure the amount of heat absorbed or released during a chemical reaction.

Before any experiments can be conducted, the calorimeter must be calibrated. This process involves running a series of tests using substances with known thermodynamic properties to check and adjust the precision of the calorimeter. Without proper calibration, the results obtained from the calorimeter can be significantly inaccurate, leading to incorrect conclusions.

In the given exercise, the experimenter's error was failing to calibrate the calorimeter before the synthesis of the compound. Proper timing of calibration ensures that all subsequent measurements are accurate, which is essential for reliable thermodynamic analyses.

Scientific Methodology

Scientific methodology is the systematic approach scientists use to ensure their research is conducted rigorously and produces reliable results. It involves several steps:

• Defining a clear research question or objective
• Conducting a thorough literature review
• Designing and conducting experiments with proper controls
• Analyzing data accurately
• Drawing conclusions based on empirical evidence

Each step is crucial for the integrity of the research process. In the context of our exercise, a misstep in calibration can be viewed as a breakdown in scientific methodology, specifically in the step of designing and conducting experiments. This emphasizes the importance of process adherence to achieve valid and reliable results in scientific experiments.

Procedural Errors

Procedural errors are mistakes that occur during the execution of an experiment, which can significantly affect the validity of the results. These errors can stem from various stages of the experimental process, including inadequate preparation, improper calibration of equipment, or misapplication of methods.

Avoidance of procedural errors is essential. This can be achieved through:

• Meticulous planning and documentation
• Consistent and thorough calibration of instruments
• Running preliminary tests to ensure methodology is sound
• Continuous monitoring and verification during the experiment

In the given exercise, the procedural error was related to the timing of calorimeter calibration. Ensuring that all equipment is calibrated before the experiment starts is crucial for avoiding inaccuracies and ensuring the reliability of thermodynamic measurements.