Disappearance of Alcohol: Observational Experiment

Aim

Observe the drying of alcohol and construct an explanation of the process.

Prior Knowledge

Pretty much none

Description of the Experiment

A piece of paper is dipped in alcohol. Observe what happens over time. Describe what you see in simple, non-technical words.

Questions

1. Write down everything that you observed during the experiment


2. What do you need to assume about the internal structure of alcohol to account for its gradual disappearance? Can it be made of one piece or should it be made of tiny pieces?


3. How could these tiny pieces disappear? Come up with multiple mechanistic explanations that could account for how and why the alcohol vanished.

For each explanation you devised above, design a testing experiment, and make a prediction of the outcome of the experiment, based on the model. For example,

Before Experiment is Performed

IF

The paper absorbed the alcohol

AND we assume...

Hypothesis

Additional assumptions

AND

We weigh the paper before it is wetted and after it has dried again

Suggested testing experiment

THEN

We would expect the paper to be heavier after the alcohol has disappeared

Prediction based on explanation/rule/idea + additional assumptions about the system

After experiment has been performed

Expected outcome occurred

← AND|BUT →

Expected outcome did NOT occur

Explanation/rule/idea has not yet been disproven

THEREFORE

← →

EITHER: We made a mistake with our assumptions, experimental set-up etc... OR Explanation/rule/idea is not valid in this regime

Using this reasoning, which explanations can you rule out?