Question

The Scottish chemist Thomas Graham observed and experimented with gas particles in the 1800s. He formulated a mathematical equation that describes the relationship between the mass of a gas molecule and its rate of effusion. This relationship is a

A. law because it describes what happens without explaining why.
B. law because it is based on mathematics.
C. theory because it describes a relationship.
D. theory because it is a description without an explanation.

i'm really not sure, I think it's law but then for this question i'm thinking its D? Can someone help me?

Answer 1

None of those answers is very good, but of them all I'd pick A. The paragraph emphasizes that Graham's Law (as it is called) is based on observation and experiment, so it would not often be called a "theory." That word tends to be reserved for relationships that are derived from mathematics, other principles, and other observations. For example, Einstein's famous equation E = mc^2 began life as a theory. Einstein worked it out using mathematics, other known law, and some principles (ideas). Only after he'd worked it out was he able to go out and test it, see if it was confirmed by observation.

In this case, it's being suggested that Graham had no preconceived idea of what the mathematical relationship between molar mass and rate of effusion should be. He just measured and determined one experimentally. I doubt it was actually that simple, but that's the presentation here. So the idea is that in THIS case, the relationship comes straight out of experiment.

You're being asked to draw a distinction between "theory" as something that goes on in your mind, an act of pure deduction and mathematics, and "law" as something that goes on in the lab, an act of pure observation and correlation. I can understand why your instructor wants to do so: to get you used to the important distinction between empirical observation and reasoning -- between, as we've said, what goes in your head and what goes on in the real world. But I can also understand your confusion, because, first, "theory" and "law" are not used in exactly that way, either in normal conversation or among scientists. We speak of the Theory of Relativity and Newton's Law of Universal Gravitation -- and yet both are equally well supported by experiment, and both involved quite a lot of math and logic in their constuction. The distinction in terms you're being asked to understand is logical -- but it's not actually used in the real world. You're going to have to get used to that, sorry.

The second point is that science itself is not nearly as sharply distinguishable. We don't have pure theory and pure experiment. Experiment unguided by any theory is usually useless. It produces results that can't be interpreted, just a jumble of numbers. On the other hand, theory unconstrained by experiment is sterile, and produces absurd and crazy fantasy stuff. In good empirical science we go back and forth between experiment and theory, observation and deduction, all the time, frequently, and any real scientific advance is always a strong mixture of both.

Answer 2

Thanks for explaining that to me, this question really confused me.