Category Archives: Fundamentals

On Science Literacy, or, Why I’m a Physicist and Not a Biologist

It’s clear from the purpose of this blog that science literacy is something I’m passionate about, and so I’m glad that it’s one of those topics that every so often bounces around the internet. While I have what I think is a clear idea of what constitutes science literacy, the science community as a whole doesn’t seem to have any consensus. Considering how poorly science education is approached at an institutional level in some jurisdictions (to wit, the hoopla around teaching evolution in some parts of the US), it’s hardly surprising that there’s no organized, vocal push for better science literacy education. Of course science literacy comes along for the ride, to some extent, with good, well-rounded science education, but it’s not necessarily a principle focus.

A surprising number of people seem to think that science literacy comes down to knowing lists of facts, as in this quiz from the Christian Science Monitor. I know it’s just a goofy internet quiz meant to generate clicks, but this is antithetical to what I think science literacy is. Rather than a measure of how many factoids and lists of data one knows, I think scientific literacy is the framework for understanding and analysing context and conclusions. Science, when boiled down to it’s essential nature, is about making connections between observations, equations and mathematics, and ideas to make conclusions. Some branches of science (say, theoretical physics) rely on equations and math to the exclusion of observations, and some rely much more heavily on observations than math. But the key component of that is “making connections.” Science literacy, then, is the ability and knowledge to be able to take a series of observations, equations, and ideas, and be able to understand how they fit together. This isn’t to say that scientific literacy is only equivalent to being an expert in all area of science, because no such person exists. But a person doesn’t need to be an expert to be able to understand basic scientific concepts, and so by extension a person doesn’t need to be an expert to be able to grasp and understand contexts and connections between concepts and facts. The trivia facts like those in the quiz are important, to be sure, but they aren’t at the kernel of understanding. They can be memorized, but memorization is not the same as comprehension.

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The Flame Challenge Revisited

Since the winner of the Flame Challenge has been announced (congratulations to Ben Ames with his animated video!), I thought I’d, for the sake of some potential feedback, publish my humble entry and comment a bit on the challenge itself. For those of you who’re not sure what I’m talking about, the Flame Challenge was an initiative spearheaded by Alan Alda which sought an answer to a seemingly simple question: what is a flame?

A flaming matchstick.

What is this?

When Alda was 11, he’d asked this of his science teacher, and the teacher replied simply “it’s oxidation,” which is a thoroughly unsatisfying answer. In an effort to get people thinking about how to make science accessible to young people, Alda challenged the science community (and anyone else who was interested) to explain what a flame was in a way that an 11-year-old could understand it. Classes of 11-year-olds all over the US judged the entries, and the challenge will now become an annual initiative (though with a different question each year).

Here’s a few short paragraphs that I submitted.

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The pH Scale

There’s a common line in soap commericals that goes something along the lines of “This soap is pH balanced, for soft, smooth skin.” The claim about the soft, smooth skin may or may not be accurate, but what does “pH balanced” mean?

The pH scale is a measurement of the acidity of an aqueous (ie, water-based) liquid compound. The capital H indicates that it’s a measurement of hydrogen ions (denoted H+ in chemical notation); the definitive meaning of the p is lost to the sands of time. A low pH value means that the solution is acidic, and has more H+ ions than OH- ions, while a high pH means the solution is basic (or alkaline — the two terms are interchangeable) and has more OH- ions than H+. The more extreme the inbalance (ie, the lower or higher the pH) the stronger the solution, and the more likely it is to eat through your skin if you spill it.

A flask and a beaker with and acid and basic fluid respectively.

The fluid in the flask on the left is more acidic than the fluid in the beaker on the right is basic.

The precise value of the pH of a solution is given by the negative logarithm of the concentration of hydrogen ions in the solution, though there are compounds that can act as catalysts in specific solutions that will alter the measured pH. Logarithms are a useful way of describing quantities that vary of a wide range of scales. Mathematically, if x = b^y, y = log_b (x).

Logarithmic equations.

Logarithms are typically either in base 10 (ie, b=10) or base e (ie, b = e = 2.718…; these are also called natural logarithms). The most commonly known logarithmic scale is the Richter scale, which measures the strength of earthquakes. The Richter scale is a base 10 scale, so an earthquake of magnitude 6.0 is 10 times stronger than an earthquake of magnitude 5.0, and 1000 times (ie, 10^3 times) stronger than an earthquake of magnitude 3.0.

Similarly, the pH scale is a base 10 logarithmic scale. A solution of pH 4.0 is ten times more acidic than a solution of pH 5.0, and 10 times less acidic (ie, more alkaline) than a solution of pH 3.0. The scale runs from 0.0 to 14.0, (explain why zero can be reached due to catalytic reactions and whatnot)

pH scale

Click to enlarge.

The pH of a solution can be tested using a variety of compounds called indicators that are known to change colour at specific pH values. Indicators do not generally interact with the solution, and so do not drastically alter the chemical mix in the solution. An indicator can be added to a solution, and then the solution can be titrated (ie, another solution is dripped slowly into the original solution to reach a desired pH) until the indicator changes colour. The colour change of the indicator indicates that the solution has reached a specific pH. Litmus paper is a crude indicator: it will indicate if a solution is acidic or basic, but does not determine exactly how acidic or basic the solution is.

In a general sense, then pH balanced, means that the solution in question has the same pH as its surroundings. Skin has a pH of around 5.5, so in the context of facial soap, the manufacturer may be using “pH balanced” to mean that the soap has a pH around 5.5, so the soap will not undergo an acid-base reaction with (and thus irritate) the user’s skin.