Chemistry: pH
The tutor introduces and defines pH, an important concept in chemistry. Most people know that neutral pH is 7. However, what is pH really, and what is it based on? pH is defined as follows: pH = -log[H+] Here’s an …
Category: chemistry
Calculator usage: using the memory on the TI-30xa
The tutor covers a simple, yet powerful feature of the Texas Instruments TI-30xa. Using the memory can save time in multi-step calculations. With the TI-30xa, here’s how: Enter the number you want to store on the display. (It can also …
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Physical chemistry: evaporation rate
The tutor’s casual observation leads to a discussion about evaporation. Last Saturday, my children and I had a water fight in the back yard. We filled two buckets (one for each side) from which to replenish our water guns. Looking …
Organic chemistry: cis and trans
The tutor gives a simple explanation of why trans fat may be disadvantageous. Cis and trans compounds have the same chemical formula but are shaped differently. With both cis and trans, a row of atoms experiences two irregularities. The cis …
Chemistry: common ion effect
The tutor tackles an essential concept of grade 12 chemistry. I introduced solubility product back in my Dec 1 post. Today the question is slightly different: How much of a salt will dissolve in a solution that already contains one …
Organic Chemistry: sn1 reaction
The tutor describes a fundamental reaction of organic chemistry. In yesterday’s post I explained the concept of solvation. While that post discussed solvation in the context of dissolving salts, solvation can also happen with organic species. In particular, you could …
Polarity: why ionic substances (salts) dissolve in water
The tutor briefly explains why water can dissolve so many salts. A salt is a compound consisting of a metal plus a nonmetal. (You can see my post here for some background, as well as related posts in my chemistry …
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Chemistry: formula unit
To confirm this definition, the tutor used both a textbook and an internet search. It’s not discussed by everybody, but the idea is useful. I navigated high school, plus three second-year chem courses (I was a math major), without ever …
Chemistry: molar volume of an ideal gas
One of the fundamental topics in chemistry is calculating between volume and moles of a gas. In chemistry, you hear people mention “at STP”. STP means standard temperature and pressure. Standard pressure is 1 atmosphere; standard temperature, curiously, is 0°C. …
Scientific notation: toggling back and forth on the TI-30XA
In high school, the tutor had a calculator much like the TI-30XA. For scientific notation, there’s probably none better. What some people call the “normal” way to write a number, is also known as “float”. So 1.35×10-3 is 0.00135 in …
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