Difficulty: Medium

Average Score: 50%

Repeated observation by others has shown that dissolving a substance in water decreases its freezing point. A student performs an experiment to determine how much the freezing point of water is decreased when antifreeze is added to it. The student adds a small amount of antifreeze to water in a beaker, and then measures the freezing point with a thermometer. The student observes that the freezing point of the water increases instead of decreasing.

What should the student do next?

Rationale

Repeat the experiment using a different thermometer to confirm the results.

The student should verify the accuracy of their findings before drawing any conclusions. Using a different thermometer can help ensure that the original measurement was not influenced by a faulty instrument, allowing for a more reliable assessment of the freezing point.

A (Change the results of the experiment to show a decrease in the freezing point of water.) YOUR ANSWER

Altering the results to fit an expected outcome is unethical and undermines the integrity of scientific experimentation. Valid scientific practice relies on accurate reporting of observations, regardless of whether they align with hypotheses or expectations.

B (Conclude that antifreeze actually increases the freezing point of water.) YOUR ANSWER

Jumping to this conclusion without further verification can lead to misleading interpretations. The unexpected result may be due to experimental error rather than a genuine property of antifreeze, necessitating further investigation before making any definitive claims.

C (Repeat the experiment using a different thermometer to confirm the results.) CORRECT

This option allows the student to check the accuracy of their original measurements. By using an alternative thermometer, the student can verify whether the initial freezing point reading was accurate, ensuring the results are reliable and reproducible.

D (Include the appearance of the solution but omit the freezing point in the lab report.) YOUR ANSWER

Omitting critical data, such as the freezing point, from the lab report compromises the completeness and transparency of the experiment. Every relevant observation should be recorded and discussed to provide a thorough understanding of the experimental outcomes.

Conclusion

In scientific experimentation, verifying results is crucial for accuracy and credibility. The student should repeat the experiment with a different thermometer to confirm the freezing point measurement, ensuring that any unexpected results are based on reliable data. This approach fosters careful analysis and supports sound scientific practices, leading to valid conclusions about the effects of antifreeze on water's freezing point.

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