A technician investigates whether certain common household processes involve chemical change. For each process, she measures the temperature of the system before and after, observes any visual changes, and records her data in the table below.
Process Initial T (∘C) Final T (∘C) Visible Observation
1. Dissolving table salt in water 22 22 Solution remains clear
2. Mixing vinegar with baking soda 22 17 Rapid bubbling, white suspension forms
3. Crushing dry ice on a warm plate –78 –62 Cloudy vapor escapes
4. Heating sugar until it turns brown 22 150 Dark brown coloration develops
Use the data to analyze each process.
(a) For EACH process (1–4), state whether the overall evidence most strongly supports a chemical change or a physical change. Justify every decision with at least two specific observations from the data table.
(b) Rank the four processes from strongest to weakest evidence of chemical change, providing a brief justification for the relative ordering of each adjacent pair in your list.
(c) Selecting the process you ranked SECOND, describe one plausible microscopic (particle-level) explanation that is consistent with all observations reported for that process.