How Chemistry and Physics\\Make Your Life Less Dirty \\
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v. 1.0.0 \\
January 2025
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\section*{Impressum}
All contents \copyright2025 Kenneth John Odle
FYI, this is made in \LaTeX\,using the report document class. It then gets exported to a letterhalf (5.5 in x 8.5 in) pdf, which then gets made into a booklet using PDF Booklet, which you can find at
I've always enjoyed cleaning, but I didn't get interested in the science behind cleaning until I ready Kate Biberdorf's \textit{It's Elemental: The Hidden Chemistry in Everything} which has an entire chapter \cite[pp.~211-233]{biberdorf2021} devoted to cleaning.\footnote{She also is from the same home town as me.}
My goal here is not to teach you how to clean everything, but how to use commonly available cleaning agents safely and effectively by teaching you how they actually do their work.
\chapter{A Chemistry Primer}
\section{Chemical vs. Physical Changes}
If you remember your high school chemistry, you'll recall that substances can undergo both chemical and physical changes. Acids, bases, surfactants, enzymes, and solvents rely on chemical changes to clean things, whereas abrasives and heat rely on physical changes. However, chemical reactions are heat dependent and tend to happen more quickly at warmer temperatures, which is just one reason we wash things with warm water—it works better.
\section{A pH Primer}
pH is a rather vague concept for a lot of people, and the internet contains a lot of misinformation and misunderstandings about how it works as a result. Let's get that sorted out.
pH is a measure of how acidic or alkaline (i.e., basic) a substance is. There is a lot of chemistry and math involved in pH, so let's start with some basic facts before getting into the chemistry and math.
\begin{enumerate}[noitemsep]
\item The pH scale goes in two directions: from 7 down to zero, and from 7 up to fourteen.
\item Substances with a pH of 7 are neutral—they are neither acidic nor basic. (They are also very rare.)
\item Substances with a pH less than 7 are acidic.
\item Substances with a pH greater than 7 are basic.
\item The further away a substance gets from 7 on the pH scale (meaning the closer it gets to either 0 or 14) the more chemically reactive a substance is. This means that it is \textit{potentially} a better cleaner, but also that it is \textit{definitely} more dangerous to use.
\item The pH scale is unitless. That is, it does not have units like centimeters or pounds or degrees. For convenience, scientists will sometimes talk about ``pH units'' when they talk about moving up or down the scale,
\end{enumerate}
\subsection{Math and the pH Scale}
The pH scale is logarithmic, rather than linear. That means that each step on the scale is multiplied or divided by a factor of ten. This can be confusing, because in our everyday lives, we are used to dealing with linear values. If one book is an inch thick, then a pile of five books will be five inches high, and a pile of 20 books will be 20 inches high.
But logarithmic scales don't work this way. They are meant to deal with values that get very large or very small and make it possible to represent them easily on a graph.
This means that something with a pH of 5 is not \textit{slightly} more acidic than a substance with a pH of 6; it's actually ten times more acidic. Likewise, something with a pH of 4 is ten times more acidic than something with a pH of 5, but it's also a hundred times more acidic than something with a pH of 6. Something with a pH of 3 would look like this:
\begin{align*}
\text{pH 3}& = 10 \times\text{pH 4}\\
& = 100 \times\text{pH 5}\\
& = 1000 \times\text{pH 6}
\end{align*}
Because the pH scale is bidirectional (that is, acidic in one direction and basic in the other), this principle also holds true for values greater than 7, but in the opposite direction:
\begin{align*}
\text{pH 11}& = 10 \times\text{pH 10}\\
& = 100 \times\text{pH 9}\\
& = 1000 \times\text{pH 8}
\end{align*}
In both of these examples, the values are getting closer to seven, which means that they are becoming less acidic (in the first example) and less basic (in the second example). They are, in effect, becoming more neutral.
From a chemical point of view, pH is the inverse logarithm of the concentration of \ch{H+} ions. If you survived high school or college chemistry, you might remember this equation:
The square brackets around the \ch{H^+}—that is, \ch{[H^+]}—just mean ``the concentration of \ch{H^+} ions''. Of course, we need to talk about what \ch{H^+} actually means.
\ch{H^+} just means ``a hydrogen atom with an electron removed'' but because hydrogen is just a single proton surrounded by an orbiting electron, this means that it's just a single proton floating around.
In reality, protons don't do all that well on their own, and tend to bond to water molecules, forming what is called a hydronium ion. The actual chemical equation looks like this:
The real question is now ``where do those protons (i.e., hydrogen ions) come from?'' One of the places they come from is from water itself, which tends to self-ionize, like this:
Notice the \ch{<=>} arrows in the middle, which indicate equilibrium. That means that this is not a one-way reaction. Instead, some water molecules are always reacting to form hydronium and hydroxide ions, and some hydronium ions and hydroxide ions are always reacting to form water molecules.
Acidic substances (like hydrochloric acid) tend to give up a hydrogen ion (i.e., a proton) readily when dissolved in water, like this:
\begin{center}
\ch{HCl + H2O -> H3O+ + Cl-}
\end{center}
and of course, that hydronium ion can react with water to release a proton, which is where pH enters into it. The more hydronium ions produced, the more protons (i.e., a hydrogen ion) floating around, which means the substance is more acidic.
The most common acidic cleaner, and also the cheapest, is good old white vinegar. Scientists usually call it \textit{acetic acid}, although its official name\footnote{according to IUPAC, that is} is \textit{ethanoic acid}. Its chemical formula is \ch{CH3COOH} and as you can probably guess, it's a small molecule that looks like this:
Most commercial white vinegar available in your local grocery store contains 4-5\% acidity; that is, most of what you are buying is water and only 4-5\% of it is actually acetic acid. Some specialty vinegars like balsamic vinegar may have an acidity level of 6\%. It's okay that these vinegars have such a small amount of acetic acid in them, since they are meant for cooking purposes more than cleaning anything.
If you head over to the hardware store, you can find ``cleaning vinegar'' which is usually around 30\% acidity. You can also buy ``glacial'' acetic acid at your local photography store (it's used as a stop bath when developing photographs), which is the purest form of acetic acid you can buy.
\section{Citric Acid}
Citric acid is commonly found in citrus fruits (hence the name). You can purchase it as a powder in the canning section of most stores, where it's used to decrease the pH of canned foods to ensure they stay safe when canned.
\section{Hydrochloric Acid}
Hydrochloric acid is pretty strong stuff (and therefore, it's pretty dangerous stuff). It's used in a number of commercially available cleaners, especially those that are meant to clean rust or limescale. You can also buy it in your local building supply center where it probably goes by the name ``muriatic acid''.
I am a bit hesitant to talk about solvents here, because commercial solvents can be strong—too strong for everyday household use. Still, there are several that are available if you know where to look, including ethanol, isopropyl alcohol, acetone, mineral spirits, and turpentine.
