However, there are instances when they can cause nuisances in the household, interfering with our daily activities. They might start to cause stress and pain. 

The only time that spiders show their aggressive nature is when they are provoked or agitated.  This usually happens when we attempt to get rid of them. They retaliate in return. When they do this, they resort to biting and secrete spider venom into the skin. 

If you enjoyed our last journey covering the differences between bee and wasp venom, join us for a new venomous journey, and the biochemistry behind it!

Are Spider Venoms Usually Very Dangerous?

The spider venom is a mix of a lot of chemicals. Usually, spider bites are not as deadly as people think.  The composition of their venom is often only enough to paralyze small animals.

So the short answer is no, besides some species that can be very dangerous or even deadly, in most cases, there is no reason to panic if bitten by a spider.

However, there are spider species like the black widow spider (Latrodectus) and the brown recluse spider (or brown fiddler) that causes more than just skin allergies. Their venom is composed of more fatal components. Those can lead to necrosis, severe skin infections, or worse. So let’s discuss what it comprises so we know how to deal with it. 

What Are the Components of a Spider Venom?

The venom is released through the spider’s fangs called “Chelicerae” as they bite. These are usually composed of the following substances. 

• Venomous Peptides: A variety of peptides (small-chain proteins) are the major components of the spider venom, some of these are venomous and in a dose high enough to harm humans, in some cases.  These peptidic toxins can serve many purposes. Among these, paralyzing small animals, or help the spider in the digestion process.
• Enzymatic and Non-Enzymatic Proteins: These, on the other hand, have a high molecular weight that usually act as agents to help spread the venom throughout the body of the bitten creature.
• Small Molecules: Different mixtures and concentrations of active small molecules can bee found in venom. The most notable ones act as neurotoxins or necrotic agents. Other active compounds like serotonin can also be found in spider venom. 
• Other Components: Spider venom has other more common substances like salts, biogenic amines, and carbohydrates.  All of these contribute to might contribute to producing pain, or have other functions.

Most people develop an allergic reaction to many of these chemicals because they are foreign agents. Plus, these can dissolve tissues and cause pain.  Depending on the components of the venom, it can either be categorized as a cytotoxin- or neurotoxin-based venom.  So what is the difference? 

Spider Venom: Is it Cytotoxins or Neurotoxins?

Two types of spider venom are found as harmful and dangerous to people. This includes venom composed mainly of cytotoxins and venom that consists of neurotoxins. The difference between these two types is obviously the nature of the main chemical components found within them and the physical damage that they cause to humans.

Cytotoxins

Cytotoxins are substances that have a toxic effect on cells.

Cytotoxins have enzymes and linear peptides that damage the cells and tissues of the prey. Insects that are charged with this venom are liquefied for the easy ingestion of the spider. In the case of humans, cytotoxins create blisters, inflammation, or lesions on the skin surrounding the bite (necrotic bite). Loxoscelism is the condition where necrosis of the skin and the spread of red blood cells occur. Other symptoms of this condition include fever, headache, and vomiting. Some of the spiders that secrete cytotoxins dangerous to humans include the recluse spider and the South African sand spider.

Neurotoxins

Neurotoxins have a toxic effect on cells, but only a specific type of cells: neurons. They are destructive to nerve tissue.

Neurotoxins present in spider venom usually are proteins, disulfide-containing peptides, or polyamines. These chemicals paralyze and then kill the prey. They attack and immobilize the nervous system. Animals can die because of neurotoxins but rarely does it happen to humans. Only in extreme situations neurotoxins from spider venom kill people. 

The condition known as Latrodectism is caused by neurotoxic venom that can cause muscle cramps, pain in the abdomen or chest, vomiting, and sweating. Out of the two kinds of venom, this is the most dangerous of all. The black widow spider or red back spider, the Brazilian wandering spider, and the Australian funnel web spider all have neurotoxins that can potentially harm humans. 

What to Do When Bitten by a Spider

Generally, spiders are harmless, but being bitten by a spider is a whole different story. The type of spider should be considered when treating a spider bite. And in extreme cases, the spider should be captured to identify the venom for the proper medical attention. This is many times not possible, so it always helps to have in mind the clearest description possible of how the spider looks like. As we said, almost always, spiders will only attack and bite when disturbed, so there should be not such thing as getting bitten while sleep without realizing.

The first aid treatment to a spider bite is to wash the affected area with soap and water. When the bite is painful and inflamed, a cold compress on the wound can be helpful. Antihistamines and analgesics can be used to reduce pain and swelling. 

Immediate medical attention is needed as soon as symptoms are detected, especially if the bite of the spider has neurotoxins or necrotic substances. The bite of the Australian funnel web, the red back spider, and the Brazilian wandering spider can be fatal to humans.

In any case, what you should not do is panicking. In most cases you are going to be perfectly fine even without serious treatment. But better be safe than sorry and if you spot any serious symptom, go get it checked out.

About the author

Jenelly Laroco is a writer for Go-Forth Pest Control. She writes about pests and how to get rid of them safely but effectively using environmentaly-friendly methods. 

The post Neurotoxin vs. Cytotoxin: The Difference between Spider Venoms appeared first on Chemistry Hall.

Making soap at home is a fun and crafty way to get some firsthand chemistry experience and enjoy the fruits of your labor.

Soap and soapmaking encompass many chemistry concepts:

• Acids, Bases and Salts
• Biochemistry: Lipids
• Organic Chemistry: Esters, Carboxylic Acids and Alcohols
• Hydrolysis
• Emulsification
• Hydrophilic/Hydrophobic Interactions

But don’t be intimidated—the actual process of making homemade soap is easier than you think!

Read on for a summary of the chemistry behind soapmaking, the chemical reaction that is used to make soap, and the science of how soap works. Most of these concepts are further expanded in any organic chemistry textbooks, which we have reviewed here.

Otherwise, skip to the bottom of the post for a simple beginner-friendly DIY soap recipe.

It is a fun experiment with kids, but always supervised! If you want to do chemistry with children, make sure to get one of the best chemistry sets for kids and adults out there!

The Chemistry of Soapmaking: Saponification

The chemical reaction that produces soap is so ancient and characteristic that its name literally means “to turn into soap”.

Saponification, from sapo, the Latin word for soap, is one of the more memorable chemical reactions learned in the first semester of organic chemistry because of its obvious applications in everyday life.

Here is a Summary of the Overall Reaction

First, we begin with a triglyceride (the fatty molecules found in vegetable oils and animal fats). A strong base is added, which breaks the ester bonds of the triglyceride into three carboxylic acids and glyceroxide. Finally, after proton exchange, the products are three carboxylic acid salts and glycerol.

Explanation of the Saponification Reaction Mechanism

Saponification is an alkaline hydrolysis of an ester. You may recall that the formation of an ester is a dehydration reaction between a carboxylic acid and an alcohol.

In biochemistry, this reaction creates a triglyceride from three free fatty acid chains and one molecule of glycerol. Saponification uses a strong base to essentially undo that reaction. We have explored this and other simple reactions in this tutorial review about organic chemistry concepts.

Remember that a carbonyl carbon, such as the one in an ester bond, has a partial positive charge due to both resonance and the greater electronegativity of the bonded oxygen. Because of this, it is a good target of nucleophilic attack by the hydroxide ion. The product of this step is an orthoester intermediate (note the negative charge on the former carboxyl oxygen).

Remember that oxygen is most stable when it has two bonds and two lone pairs of electrons. Its electrons rearrange in order to achieve this stability, reforming the double bond with carbon to make a carboxylic acid and expelling the other half of the ester as an alkoxide, in a second step called “elimination” (the conjugate base of an alcohol).

We know that alcohols in general are very weak acids. Their conjugate bases, alkoxides, are therefore quite strong. As a result, proton exchange takes place, and the acidic proton of the carboxylic acid is readily donated to the alkoxide. This results on the formation of an alcohol, plus the sodium or potassium salt of the carboxylic acid.

Products of Saponification

This same reaction is occurring at all three ester bonds in a triglyceride during saponification. The three resulting fatty acid salts are also known as soap salts. Their properties are highly dependent on the number of carbons in the fatty acid chain and the degree of saturation.

Longer carbon chains (stearic acid, C18, for instance) tend to yield soaps that are harder and less soluble.

On the other hand, unsaturated fatty acids will yield a softer soap with a lower melting point. Some fatty acid salts are more cleansing than conditioning, and vice versa. Similarly, some will work up a nice, rich lather, while others will not. It’s important to consider these effects when deciding which fats and oils to use in a soap recipe.

How does soap work?

Take a look at the molecular structure of this soap salt:

Is this molecule polar, or is it non-polar? The answer is, both! At the top right, the carboxylate, acting as the anion in this sodium salt, is a very polar functional group. However, the rest of that long hydrocarbon chain is non-polar.

This type of compounds are called amphipathic.

Everyone knows that oil and water don’t mix, but not everyone knows that the reason for this is the polarity (or lack thereof) of each substance. As a chemistry student, you have probably already learned that like dissolves like, and that polar molecules are hydrophilic (water-loving) while nonpolar molecules are hydrophobic (water-fearing).

You can probably see where this is going… Soap works by allowing hydrophobic substances, like grease and oil, to dissolve in water. Its two ends, one polar and the other nonpolar, allow it to mix with both water and oil. It does this by forming tiny spherical structures called micelles.

In this cross-section of a micelle, you can see the hydrophobic (nonpolar) hydrocarbon chains inside the sphere, while the hydrophilic (polar) ends form the surface. When you wash a greasy pan with soapy water, the grease is attracted to the hydrophobic ends, trapping it inside these micelles. Since the surface of the micelle is polar, it is soluble in water and can now be easily rinsed away.

Soap is also a natural surfactant, which means it reduces the surface tension of water, effectively making water “wetter”. The “wetter” the water is, the better its solvent properties are, and the better it cleans.

Chemistry at Home: How to Make Your Own Soap

Now, let’s put all this chemistry knowledge into action and make some homemade soap!

This DIY (do it yourself) soap recipe is a very basic one that is perfect for beginners. You will need some basic equipment and a few easily accessible ingredients:

Soapmaking Equipment

• Safety goggles and gloves
• Kitchen scale
• Pitcher*
• Jar*
• Large pot or bowl*
• Thermometer
• Mixing spoons*
• Immersion blender (stick blender)
• Rubber spatula
• Soap molds

* Make sure you use nonreactive materials, like plastic or glass.

You can find our personal recommendations on home chemistry labware here. It would be ideal to be able to use appropriate beakers or flasks for this experiments. But if you don’t have access to those yet, you can get away with the household items listed above.

Lye is caustic (very basic) and can react with many things, as metals (or you skin!). This reaction is exothermic, and the rapid temperature change may cause low-quality glass containers to crack.

Basic Soap Ingredients:

• 500 g of olive oil
• 100 g of coconut oil
• 80 g of lye (NaOH, caustic soda)
• 200 mL of water

Keep in mind that, while you can use practically any type of oil or fat to make soap, they will have vastly different properties and may require different amounts of lye. If you use different oils, make sure you use a lye calculator to ensure you aren’t using too much. Having excess oil in your soap is not a big deal, but having excess lye is!

Instructions:

1. Prepare the lye/NaOH solution. Weigh the water in the pitcher. Separately, weigh the NaOH into the jar. Then, slowly add the NaOH to the water. DO NOT ADD THE WATER TO THE LYE! Remember how they made you memorize “add acid to water, not water to acid” in your chemistry lab’s safety module? The same goes for bases. A strong base like NaOH is highly reactive by definition. That means a LOT of energy is released when it makes contact with water. If you do this step backwards, the mixture will quickly heat up. This might end-up in a caustic soda geyser, which can easily cause a chemical burn. When you add NaOH to water, there will still be heat release, but it will be much less dangerous. Carefully stir to dissolve (rinse the spoon immediately after mixing). This solution can get to almost boiling temperature all by itself, so you may need to allow it to cool down slightly until you can easily handle the pitcher.
2. Weigh out and mix your oils in the pot or bowl. This will be easier if you warm the coconut oil up a bit first until it melts.
3. Carefully add the NaOH solution to the oil mixture and gently mix with a spoon until it gives an homogeneous mixture.
4. Now you can pull out your stick blender and start the emulsifying process. Remember, you are blending a highly caustic mixture right now, so keep your distance and try not to splatter.
5. After a few minutes of blending, the mixture should start to thicken, indicating that the saponification reaction is underway. Optionally, this is when you can add other ingredients to customize your soap, like essential oils, colorants, mix-ins, etc. Otherwise, you can proceed with transferring the soap to whatever you are using as molds. Silicone baking molds work great for this. Use a rubber spatula to get every last bit out and facilitate cleanup.
6. Let your soap harden for at least 24 hours before trying to remove it from the mold. Once it is hard enough to handle, you can cut it into different shapes/sizes if desired.
7. Finally, the soap needs to cure for about one month to be sure the saponification reaction is complete and to dry out the excess water. Once it’s fully cured, you can enjoy using your homemade soap!

And that is pretty much it! As you can see, it is an easy procedure.

Now that you know how to make your own soap, and you understand the chemistry behind it, time to put the experimental procedure into practice!

Let us know in the comments if you have any question or suggestion. Also, feel free to share the results of your first batch of soap!

The post How to Make Your Own Soap at Home (with Chemistry!) appeared first on Chemistry Hall.

I hear the same discussion pop up form time to time among both chemists and non-chemists: why does some people’s urine smell funny after eating asparagus?

A lot of people claim to never have experienced this phenomenon. Then, they incorrectly assume that it is because they do not metabolize the chemical components of asparagus the same way. This is not completely true.

But for starters, what are the chemical components of asparagus?

The Chemical Composition of Asparagus

Chemophobia is present all over the place these days. People don’t realize that everything is made up of chemicals. A lot of badly-informed people would be shocked if they took a quick look at the actual chemical composition of completely natural foods, such as asparagus.

Check out the ingredients list of asparagus! This picture was taken out of the book called “Molecules: The Elements and the Architecture of Everything“. This is a great chemistry reading, by Theodore Gray and Nick Mann.

But out of that huge list, we actually just need to look at one ingredient: asparagusic acid.

What is Asparagusic Acid, and Does it Make our Urine Smell?

Asparagusic acid is a carboxylic acid which has a disulfide group as a part of a five membered heterocyclic ring.

Even though asparagusic acid is a organosulfur compound, it doesn’t really smell bad. As a matter of fact, asparagusic acid is just the precursor of different sulfur-containing volatile metabolites.

Usually, compounds such as carboxylic acids have low volatilities. For us to detect a smell, we need the responsible compound to be airborne.

The boiling point of asparagusic acid is 324 ºC, so even if it really smelled bad, it would have a hard time reaching our olfactory receptors. Actually, this compound was both isolated and prepared synthetically in a chemistry lab, and it does not show the typical asparagus pee smell.

Total Synthesis of Asparagusic Acid

A convenient laboratory total synthesis of asparagusic acid was reported by Yanagawa and co-workers in 1973. They started by treating a readily available diethyl malonate diol derivative with hydrogen iodide. This allows carrying out, at the same time, iodination of both alcohols, and a single decarboxylation.

After hydrolysis of the resulting monoester, the first intermediate with two iodines is obtained. Reaction of this intermediate with sodium trithiocarbonate (Na₂CS₃) gives the corresponding dithiol after treatment with sulfuric acid.

Finally, oxidation using DMSO at high temperature gives asparagusic acid. This organic synthesis, leads you to the desired compound in just three steps.

We have confirmed that asparagusic acid is not smelly. So, what does actually cause the asparagus pee smell?

When we eat stuff, we metabolize its chemical components, and the (bio)chemical transformations that take place in our body, generate new chemical compounds. The compounds generated after eating and processing asparagusic acid, together with the asparagus pee smell gene, are the two players that cause this unpleasant sensation for many people.

What is the Asparagus Pee Smell Gene?

So, our bodies break down asparagusic acid into smaller sulfur-containing molecules, which are smelly? That’s it?

Reality is, there is a gene that controls if each human being is able to smell or detect the metabolites that make asparagus urine smell. This is what we call the asparagus pee smell gene.

We have already covered this briefly in our list of explanations to 100 fun chemistry facts, but we felt that an entire post for this one may be useful and interesting.

This gene makes the whole story complete. Not all of us can smell the asparagusic acid metabolites. So even though it seems like not all of us produce them, we actually all do! It is just that some of us cannot smell them.

You can read further in this study published in Chemical Senses. The summary is that, actually, there are individual differences in both the production AND detection of the cabbage-like smell of asparagus-pee. The biology associated with metabolite production is mostly unknown. However, the inability to smell these metabolites is identified in association with an individual nucleotide polymorphism. This is what we refer to as the “asparagus pee smell gene”.

If you look really closely, it seems that there are many variations of these two traits: some people actually produce very small amount of these compounds, which can be enough to be detected by some, but not by others. So it is not a matter of black or white, there are intermediate situations.

A recent online survey with almost 3000 participants, showed that around 70% of the population can detect the smell in their own urine after eating asparagus.

Which Are the Chemicals that Actually Smell Bad in Our Urine?

A lot of small organic molecules containing sulfur atoms have a particular unpleasant smell.

For example, tert-butylthiol is used in very small concentrations to give natural gas (which is odorless by itself) a detectable smell. But in higher concentrations, I can tell you that it is extremely unpleasant. I’ve seen labs evacuated for the day after a few microliters of the stuff were dropped out of a fumehood.

Not tert-butylthiol, but different volatile compounds are produced while metabolizing asparagusic acid. Many structures have been proposed over the years. As far as 1891, it was proposed that methanethiol was the responsible of this smell. More recently, gas chromatography analysis allowed detection of different volatile organo-sulfur compounds arising from the metabolism of asparagusic acid:

Some compounds showing the functional groups in the table above, smell extremely bad in high concentrations. However, our ability to detect them in the amounts in which are metabolically produced by our bodies, depends on this asparagus urine smell gene.

I Got the Asparagus Pee Smell Gene: Can I Neutralize Asparagus Smell?

Maybe you enjoy eating asparagus. But also maybe, thanks to the asparagus pee smell gene, you are unlucky enough to be able to detect very low concentration of the sulfur metabolites.

To be fair, most people report the fetid odor going away quite quickly: you will naturally pee once or twice with the smell before it disappears.

Disappointingly, there is no clear way of making the smell go away quicker. The rate at which you get rid of metabolites through your urine depends on your glomerular activity (kidney filtration rate). This is not really accelerated by drinking more water or by other home-remedies.

However, drinking a lot of water will definitely dilute your urine and turn the smelly sensation milder.

But there is no big short-cut other than not eating asparagus!

Are There Other Foods that Make Your Urine Smell?

Asparagusic acid is a compound that is found almost only in asparagus. But other foods, such as Brussels sprouts, also have sulfur-contaning precursors that give rise to smelly metabolites.

Other foods can act as dyes for pee, making your urine colored. For example, don’t be surprised if your pee turns pink/red after eating beets or blackberries!

If you are interesting in other food-related stories such as these, you really need to get a copy of “Why Does Asparagus Make Your Wee Smell? And 57 Other Curious Food and Drink Questions” by Andy Brunning.

This is a great read for any science student or enthusiast. It can be enjoyed by all audiences: from kids at school to professional chemists. We were really inspired by that book for writing this post.

Asparagusic Acid and the Asparagus Pee Smell Gene: Conclusion

In conclusion, there is a combination of two factors that allow you to smell this annoying “asparagus urine smell” or not:

Asparagusic acid gets metabolized to different extent by different individuals, giving smelly volatile organo-sulfur compounds. On the other hand, there is a gene that determines our detection threshold for these compounds. Some people detect very low concentrations, and others are just lucky and simply can’t detect them!

The post The Asparagus Pee Smell Gene (Chemistry Behind the Scenes) appeared first on Chemistry Hall.

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