Household chemicals and a dubious infographic

Source - James Kennedy's blog

I searched James Kennedy's blog for the original source of this graphic, and I can't find it at all.

I searched for bleach and vinegar and household and a whole bunch of other terms that are listed here, but the graphic - still hosted on his site - and its original post is entirely missing from his site. The graphic's host address suggests that it was posted sometime in 2013, and I've been through every on of his 2013 posts (he claims to have read and reviewed 103 books in that year, and I scanned every single one of this review posts, blech).

I'm curious as to why he might've taken the graphic down, and I have an idea.

The graphic is woefully undersourced and possibly dangerous.

To quote the graphic...

This chart summarizes how people in internet forums are using various combinations of household chemicals to make stuff on their own. Sources include YouTube, Yahoo! Answers, and countless niche internet forums. Because all the information was gleaned from the Internet, I cannot accept any responsibility for its accuracy or efficacy.

This table is provided for viewing only. Do not use attempt [sic] any of the household chemistry on this chart. I accept no responsibility for damage incurred as a result of using the information provided in this chart.

Admittedly that's a much easier way to post an infographic: say that it might or might not be correct and claim that nobody can sue you if they get hurt using the information you provided. That seems incredibly irresponsible and foolish coming from someone who claims to be somewhat of an expert in the chemistry field (and whose work I've posted before).

I'm not going to make any claims as to the veracity of the infographic up there. In fact, I'm going to say flatly that I don't trust it because there aren't any sources presented.

Some of the 'answers' - the water line, the bleach/ammonia combo, the bleach/soap combo - are most assuredly correct. Others - the hydrogen peroxide/liquid soap, salt/vinegar, whatever 'washing up liquid' is - are partially but certainly not entirely correct. And others are almost assuredly wrong - rubbing alcohol/cornstarch makes shampoo?

Today's lesson is that just because something is written and presented neatly, it isn't automatically correct.

CERAMIC COATINGS - How It Works | SCIENCE GARAGE

First off, thanks to Eric Moorman who sent me this video. Mad love for Eric.

Let's go through the material science awesomeness in this video about how to get the most durable, prettiest finish on your car.

• The first four minutes or so are all about the causes of the tiny scratches on car surfaces and how to clean the car before applying a finish coating of either wax or ceramic.
• At 4:10 we get a discussion of wax, and the host even uses the word hydrophobic, explaining how the water beads up because of the hydrophobic nature of the wax.
• At 5:10, we finally get to the ceramics, "a non-metallic solid material making up an inorganic compound of metal and nonmetal (or metalloid) atoms primarily held in ionic and covalent (?) bonds." The host explains that those atoms can be crystalline (in various ways) or even vitrified.
• There's an explanation of the Moh's hardness scale, and a mention that there are other ways to measure hardness like via measuring scratch resistance.
• Heck, he even shows a very simplified version of covalent bonding with shared pairs of electrons.
• We get into using nanotextures to increase the hydrophobic character of a surface, increasing the contact angle between a drop and the surface - with a nice diagram, too - explaining super hydrophobic coatings.

Admittedly, I had no idea such coatings existed for cars.

Things not to mix

TL; DR - The first two are bad. The third and fourth are very minor worries.

I came across this graphic online and thought I'd take a moment to check the chemistry involved.

Let's go in order, and I'll cite sources as I find them...

From ThoughtCo.com...regarding bleach + vinegar

What Happens When Bleach and Vinegar Are Mixed 

Chlorine bleach contains sodium hypochlorite or NaOCl. Because bleach is sodium hypochlorite dissolved in water, the sodium hypochlorite in bleach actually exists as hypochlorous acid: 

NaOCl + H₂O ↔ HOCl + Na⁺ + OH^-

Hypochlorous acid is a strong oxidizer. This is what makes it so good at bleaching and disinfecting. If you mix bleach with an acid, chlorine gas will be produced. For example, mixing bleach with toilet bowl cleaner, which contains hydrochloric acid, yields chlorine gas: 

HOCl + HCl ↔ H₂O + Cl₂ 

Although pure chlorine gas is greenish-yellow, gas produced by mixing chemicals is diluted in air. This makes it invisible, so the only way to know it's there is by the smell and negative effects. Chlorine gas attacks mucous membranes in the eyes, throat, and lungs—these attacks can be deadly. Mixing bleach with another acid, such as the acetic acid found in vinegar, yields essentially the same result: 

2HOCl + 2HAc ↔ Cl₂ + 2H₂O + 2Ac^- (Ac : CH₃COO) 

There is an equilibrium between the chlorine species that is influenced by pH. When the pH is lowered, as when adding toilet bowl cleaner or vinegar, the ratio of chlorine gas is increased. When the pH is raised, the ratio of hypochlorite ion is increased. Hypochlorite ion is a less efficient oxidizer than hypochlorous acid, so some people will intentionally lower the pH of bleach to increase the oxidizing power of the chemical even though chlorine gas is produced as a result.

So, I'd say that one checks out.

Next up, bleach and ammonia...again, from h2g2.com...

When these two compounds are combined, the following reaction takes place:

2 NaOCl + 2 NH₃ --> 2 NaONH₃ + Cl₂

...

Another potential reaction, which occurs when a greater amount of bleach is added than ammonia, is this:

3 NaOCl + NH₃ --> 3 NaOH + NCl₃

That's sodium hydroxide and nitrogen trichloride. Nitrogen trichloride is a very toxic chemical to humans, and even if you did get close enough to ingest it, it would probably explode in your face first, as it is also a very volatile explosive.

...

Still another reaction - in three parts this time - can occur, producing hydrazine, N₂H₄, a component of rocket fuel) if you have more ammonia than bleach:

NH₃ + NaOCl --> NaOH + NH₂Cl

These two products then react with ammonia as follows:

NH₃ + NH₂Cl + NaOH --> N₂H₄ + NaCl + H₂O

One last reaction occurs to stabalise the reagents:

2 NH₂Cl + N₂H₄ --> 2 NH₄Cl + N₂

That last equation is of particular interest because of the amount of heat it produces. The heat is so great that it usually leads to an explosion.

Again, I'm okay with staying you definitely shouldn't mix those two. I did, however, struggle to find a source with reactions that I trusted. The first two I found - this and this - didn't make sense in a few places, having missing mass in various places in their reactions.

Now, bleach + rubbing alcohol...

I'm a little less sure about this one. I found a lot of sources that say this one produces "chloroform, (CHCl₃), hydrochloric acid (HCl), and other compounds, such as chloroacetone or dichloroacetate." but I can't find the exact chemistry anywhere.

The only reaction I could find, however, in all of the articles was of acetone with bleach.

3 NaClO + C₃H₆O --> CHCl₃ + 2 NaOH + NaOCOCH₃

Acetone and isopropyl (rubbing) alcohol certainly aren't the same thing. So I'm going to leave this one as a maybe as I also found a fair number of sources that said any reaction between isopropyl alcohol and bleach would be fairly slow and likely would need a catalyst to see significant product production at room temperature.

The last combo is hydrogen peroxide with vinegar (acetic acid). From wikipedia...

[Peracetic acid] forms upon treatment of acetic acid with hydrogen peroxide with a strong acid catalyst.

H₂O₂ + CH₃CO₂H ⇌ CH₃CO₃H + H₂O

From cooksinfo.com

If you mix the two together in one bottle, a weak form of peracetic acid is formed. Peracetic Acid ( aka peroxyacetic acid) is a mixture of acetic acid and hydrogen peroxide. Peracetic Acid is primarily used for deactivation of a large variety of pathogenic micro-organisms in the industrial food industry, medical supplies and to prevent biofilm formation in paper pulp industries. It is usually produced in concentrations of 5 – 15%. This industrial formulation is toxic by inhalation, ingestion or if absorbed through skin; caustic and corrosive at concentrations > 10%; irritant at concentrations below 2%. Retail vinegar is a mixture of acetic acid and water composed of 4 to 8% acetic acid. Hydrogen peroxide at 3 % and retail versions of vinegar are an extremely diluted form of peracetic acid. Mixing the diluted form of acetic acid (known as vinegar) with 3% hydrogen peroxide forms a weak form of peracetic acid that may cause some reaction to those who are very sensitive to it – another reason, besides effectiveness, that applying the two solutions separately is recommended.

So this one I'm going to say is true but a minor issue.

Seriously, though, the first two combos - bleach with either vinegar or ammonia - are bad combos and are to be avoided. The other two, maybe less so...maybe.

Fire in ZERO-G!!

Dr Derek, please stop using multiple exclamation points and all caps in your video titles.

I get that you're trying to game the YouTube algorithm, but it's kind of off-putting for me.

(Ok, rant over, back to the science content...)

I would love to ride the vomit comet. It's certainly a secondary dream to actually getting to go into space, but I'm pretty sure the 'space' goal has entirely left the building at this point.

Apparently having a really successful YouTube science education channel offers a few more opportunities, and Dr Derek got to ride the parabolic flights simulating weightlessness, something that let him explore fire in 'zero-gravity' environments.

Once he explains the why of his experiments (without weight, the isn't a buoyancy force to move less dense objects like hot air upward and more dense objects like cold air downward), everything makes sense, but I absolutely couldn't have come up with that explanation.

Luckily, I don't have to teach this...and if I ever do, I plan to just show this video.

You rock, Dr D.

(Oh, the fire doesn't actually show up until about 3:40 in the above video. Before that it's explaining how the plane work to simulate zero gravity and some playing around inside the plane.)

In case you're curious, here's Physics Girl's video from the same flight.

Luca Parmitano and Chris Cassidy explain what happened during EVA 23

tl; dw - Luca almost drown in his spacesuit...but he didn't.

Water does some freaky stuff in space. Apparently, some of that freaky behavior edges toward being deadly to astronauts.

In this case, Luca Parmitano was on an extra-vehicular activity (EVA - a thing most folks might call a spacewalk) and had a small water leak into the air flow refreshing the air into his spacesuit's helmet. (Skip to 2:45 to get the explanation from astronaut Chris Cassidy) The small leak began to build up behind the plastic shield behind his head. When the water built up enough, it started to leak around the plastic shield and touched his snoopy cap. I guess the snoopy cap is hydrophilic, because the water then quickly headed forward, covering his head, filling his ears, and eventually drenching his eyes.

The next stop for the water would have been to cover and fill his mouth, leading nicely to - as all involved feared - death...in space...from drowning.

Turns out water's IMFs really matter because the molecules hold together well enough that they're hard to get off of a head in space without hands or towels - both well on the outside of the helmet.

I did appreciate seeing (at 1:30) the other astronauts (Russian, American, everybody on the ISS) at the ready to help save Luca once he got back into the airlock.

Plus seeing Karen Nyberg's hair in space is just outstanding.

Elephant toothpaste

Today's topic is the reaction typically known as elephant toothpaste.

It's a pretty simple reaction, the decomposition of hydrogen peroxide solution into water and oxygen gas.

H₂O_{2 (aq)} --> H₂O _(l) + O_{2 (g)}

This reaction happens all the time, most commonly in your home in that brown bottle of 3% hydrogen peroxide solution that somebody bought years ago and that goes 'pfsssst' whenever you open the cap.

The 'pfsssst' is the built-up oxygen gas.

In the demonstrations below (and after the jump with much bigger volumes), that reaction is catalyzed (sped up) by the addition of various things - typically sodium or potassium iodide but also yeast. And the oxygen gas is contained within soap bubbles.

Add that all together - maybe add in some food coloring - and you get a foamy mess.

...on Jimmy Kimmle's show...



...on The Big Bang Theory...



...a supposed world record volume...



...another supposed world record volume...



...another supposed world record volume...

A better description of entropy

I open my discussion of entropy in AP chemistry by saying that I'm going to offer an incorrect definition of entropy, that it's the same incorrect definition I was taught in high school and that my students will likely be told in college - as I was - that the high school definition isn't correct...that it's a drastic simplification.

I've said this for years, and I've had other people who study chemistry in college confirm that same story having happened to them, too.

I also will admit that I tried to read PF Atkins's The Second Law without much success.

So, let's try to be a little more precise and correct by watching Steve Mould's video up above - it's a video explaining how a Sterling engine works - and try to be better about what entropy really is.