Good day, gentle readers:
I’ll be honest. In spite of the Pollyanna-ish pronouncements of education gurus—and the shareholders of Zoom—online Chemistry teaching is far less than ideal. I get it: we’re doing our best inside a set of rules that none of us asked for.
What can we do? A lot.
The two things that will pretty much hook a student to his or her SMART-phone during an online class—and after class—are boredom and frustration.
Boredom needs no explanation; we were all (Chemistry) students. A bored student is not an engaged student, and likely not a student who wants to learn. If I got a nickel for every time that I thought “How can I make this lesson engaging?”, I wouldn’t need to buy lottery tickets.1 Online teaching-wise, I’m finding YouTube videos2 to substitute for labs and demonstrations. These can be very good, but I’m not gonna lie: When someone teaches for me, I’m usually not a fan. So I frequently voice over the vids.
If I can get students to try a lab activity at home3, so much the better.
But outside of a face-to-face classroom, our skills as instructors—as explainers—are stretched. ‘Cause if students don’t understand the concepts we’re teaching, how can they study? How can they learn? A lack of understanding can, in many cases, result in frustration.
And frustration = a “checked out” student, especially if video games are available.
Now, more than ever, my PowerPoint lessons are written as stand-alones. Sure, I screen-share during online lessons, with tons of commentary, analogies, encouragement, cajoling, and lame jokes. But, to use that hackneyed phrase, “at the end of the day”4—the PPT lesson—on its own—has to be enough to engage the student and to foster understanding.
I tend to prepare my own handouts, rather than assign textbook questions. There is nothing like a custom-made, teacher-prepared handout to get ‘em interested. I recently prepared a handout on solute concentration as it applies to one’s bloodstream that you can see below as an example. See the Supporting Information to download a copy.
Enough, already, with the Mole and Concentration Questions
Dietary and vitamin supplements—nutraceuticals—are definitely a “thing”.
In 2019, the global nutraceutical market was estimated at USD 382.5 BILLION per year.5 That’s right, folks, 3.825 TRILLION or 3.825 x 1012 or 3,825,000,000,000 US dollars per year—worldwide—for anything from vitamins to probiotics to herbal remedies to amino acid supplements to hair-loss tonics.
That’s roughly the GDP of Germany, for Pete’s sake.6
Vitamin D3, aka cholecalciferol, C27H44O, is illustrated below. Vitamin D3 is a fat-soluble vitamin made by the skin in response to sunlight, and is found in foods such as salmon, red meat, and egg yolks. Vitamin D3 is often added to yoghurt, milk and breakfast cereals. These foods are labelled “vitamin D fortified”.
Vitamin D3 may also be taken as a dietary supplement; a typical dose is 25 micrograms per day. (1 microgram = 1 μg = 1 x 10–6 g).
1. a) Convert 25 μg of vitamin D3 to moles, and to quantity of molecules. b) Blood volume in men is typically 75 mL∙(kg body mass)–1. For a 63 kg man, calculate the [vitamin D3] in the bloodstream, in mol∙L–1 and in molecules∙L–1, after ingesting 25 μg of vitamin D3. Assume all of the vitamin D3 is in the bloodstream.
2. By comparison, many people take 1,000 mg of vitamin C per day. Vitamin C is also known as ascorbic acid (176.1 g∙mol–1), and is water-soluble. (1 mg = 10–3 g)
a) Convert 1000 mg of vitamin C to moles, and to quantity of molecules. b) Blood volume in men is typically 75 mL∙(kg body mass)–1. For a 63 kg man, calculate the [ascorbic acid] in the bloodstream, in mol∙L–1 and in molecules∙L–1 after ingesting 1000 mg of Vitamin C. c) What assumption is implicit when one solves part (b) above?
3. A 63 kg man has a blood glucose concentration of 4.5 mmol∙L–1 (1 mmol = 1 millimol = 10–3 mol).
a) Calculate the total mol of glucose, C6H12O6, in his blood.
b) Calculate [glucose], in molecules∙L–1 in the blood.
c) What mass, in grams, of glucose is in his blood?
4. a) Using your answers to the questions above, which of vitamin D3, vitamin C, or glucose is present in the greatest molar concentration the bloodstream? State your answer in terms of a simple ratio—list the lowest concentration as “1”. How does molar concentration relate to molecular concentration? b) Look at the relative concentrations; ask some questions: Why is the typical vitamin C concentration in the bloodstream ca 105 X higher than vitamin D3? (If your Mom/Dad is a physician, why not have a conversation?)
I’ll end by wishing everyone well in his or her battle with Zoom.
Feel free to get in touch if you want to take a chance with one of my PowerPoint lessons or labs or handouts.
May peace be with you . . .
- I don’t.
- May I suggest “The Periodic Table of Videos” channel?
- Today we did a “lab” on the reaction of Alka-Seltzer (A-S) with varying solutions of vinegar and water to determine the percentage by mass of NaHCO3 in an A-S tablet.
- Don’t get me started . . .
- Market value of nutraceuticals in the United States from 2014 to 2025, Statista (accessed 5/4/2021)
- Germany’s 2020 GDP was USD 3.78 x 1012; List of countries by GDP (nominal) Wikipedia (accessed 5/4/2021)