26 votes

Is there such a thing as a "minimal soap" molecule?

It boils down to the definition of soap. Wikipedia defines a soap as the salt of a fatty acid. IUPAC claims the smallest fatty acid can be considered to have 4 carbons. Therefore the simplest soap ...
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18 votes
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Why does shampoo lather much more the second time it is applied?

Quoting a reddit post from chemist nallen: The short answer is that the dirt and oils from your hair compete for the surfactants making them less available to form lather, which is small bubbles. To ...
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  • 666
14 votes
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What is the purpose of froth in washing clothes?

The froth has little or no effect on the detergent action. In fact detergent manufacturers have to add anti-foaming agents to stop excessive foam generation in automatic washing machines. Froth/foam ...
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  • 1,943
14 votes
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What are "tensides"?

I don't remember to have seen the term tensid outside the context of the German language. The term is typically applied to agents that decrease the surface tension (hence tensid) of water. Note that ...
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11 votes
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What turns clear liquid soap blue?

The color of the precipitate is strongly reminiscent of copper(II) hydroxide. I hypothesize: Chloride corrosion of copper from exposed brass (ref 1 || ref 2) a. Per ref 2 above, sulfate may also ...
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  • 16.9k
10 votes

Quantifying soapiness; there's pH, pKa and pO2, is there a p_soap or p_surfactance?

A concept that captures how effective a detergent is at doings its job is aptly called "detergency." As might be expected this is a complex property and difficult to describe unambiguously ...
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  • 19k
8 votes

Soap and rain water, why does it not rinse off?

Yes, this is a good explanation. Rain water is almost pure water, it lacks of bivalent ions such as $\ce{Ca^{2+}}$ and $\ce{Mg^{2+}}$ which helps soap to rinse of. You will get the same effect when a ...
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  • 928
8 votes

Is there such a thing as a "minimal soap" molecule?

While I agree that the definition matters I disagree with the definition of soap as "as the salt of a fatty acid". For one SDBS, AOT, SDS, Cocamide DEA (not even a salt) and CTAB are all popular soaps ...
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  • 12k
8 votes
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Is it possible to store a Tween 80 stock solution?

The Sigma Aldrich/Merck product information for "TWEEN® 80 solution" states the following: Storage/Stability Aqueous solutions of polysorbates as well as the neat liquid will undergo ...
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  • 500
7 votes
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Is there a type of detergent/surfactant that evaporates at STP?

Volatile surfactants There are many molecules that are both surfactants (in water) and volatile, but of the ones I can think of, none can be used safely in home laundry applications. Hydrocarbon ...
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  • 20.3k
7 votes

Quantifying soapiness; there's pH, pKa and pO2, is there a p_soap or p_surfactance?

Soapiness or anything like that cannot be represented by a single number. Hence no point in inventing such a quantity. Just like we cannot associate a plain number to odors, soapiness is ...
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  • 33.1k
6 votes

Do surfactants exist in a gas phase?

I am wondering if there are surfactants that exist in a gas state that can be used to reduce the surface tension of a liquid. The most direct answer is "no". Gases do not have surface tension and ...
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  • 20.3k
6 votes

How do I lower the surface tension of water without using a detergent?

Your goal is to reduce the surface tension of the water so that it does not support the formation of large bubbles or inhibit the whetting of the dirt particles. When the bubbles are small, the ...
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  • 16.8k
5 votes

How does NaCl (or any inorganic salt) increase surface tension?

I hope this picture helps. The interaction between a molecule of water and an ion is stronger than the hydrogen bonding that occurs between two water molecules.
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  • 750
5 votes
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What non-poisonous chemicals can get rid of SLS effectively?

SLS is highly soluble in water (100g/L) Therefore, in the specific case of your teeth having lots of bubbles around them after brushing, you should simply gargle your mouth with water to remove the ...
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  • 330
5 votes

Biodegrability of straight chain and branched chain detergents

According to Scott and Jones1: ... problems arise with branched alkyl chains, a side chain methyl group or a gem-dimethyl-branched chain cannot undergo β-oxidation by microorganisms and must be ...
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4 votes
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The sponge isn't foaming up, why?

Tap water contains calcium and magnesium ions; more so if the water is hard. These ions can bind to soap over time and make an insoluble soap curd. Is the sponge clean? If not, another reason is that ...
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  • 5,487
4 votes
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Why isn't washing up liquid dry

There's no technical reason why you couldn't make a powdered dishwashing detergent and I suspect that someone probably does sell it, just as there are liquid, tablet, and powdered automatic dishwasher ...
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4 votes

What exactly happens while washing clothes

When you wash a piece of cloth, even without soap, it's better to agitate. The vibration, friction, etc. will help speed up the process of mixing the dirt/grease with water. Even the very definition ...
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  • 247
4 votes

How do I lower the surface tension of water without using a detergent?

Vinegar does reduce the surface tension quite a bit. If you put a tablespoon or two of vinegar in a bowl and then run water into it, the bubbles that form on the surface persist much longer than they ...
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  • 16.9k
4 votes

How to disperse salicylic acid in sodium lauryl sulfate solution?

I don't have a lot of experience with salicylic acid as I'm just starting to work with it myself at the moment. However, I find that it disperses better if it is added to the solution at a high ...
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4 votes
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Can cationic species form micelles?

Cationic micelles similar to your examples can and do exist. For example cetyl trimethylammonium bromide (Growth of Cationic Micelles in the Presence of Organic Additives, P. A. Hassan and J. V. ...
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  • 16.8k
4 votes
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Why does Dead Sea water feel greasy?

I don't know what you mean by the term "greasy", but here's a possible explanation: When Dead Sea water evaporates on skin, then salts will precipitate when their maximum solubility is reached. The ...
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  • 6,799
3 votes

What exactly happens while washing clothes

The modern definition of washing is "washing can be defined as both the removal by water or aqueous surfactant solution of poorly soluble matter and the dissolution of water-soluble impurities from ...
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  • 33.1k
3 votes
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Lemon juice, the ultimate anti-foaming agent?

A lemon has an oil that is present mostly in the skin. For instance if you squeeze lemon into hot tea in a styrofoam cup and let the tea sit, then you'll see a surface roughness at the liquid level. ...
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  • 21.6k
3 votes

What are "tensides"?

I have seen the term "tensider" (likely meaning "surfactants") on labels in Swedish too, this is probably because Swedish is a Germanic language. All sources I could find seem to confirm that it is ...
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3 votes

Why do surfactants lower the surface tension

We usually say that at an interface, molecules will orient themselves at a "preferred" position, but we usually ignore that such a "preferred position" can actually be their "least unfavorable" ...
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  • 2,874
3 votes

Difference between Soap and Detergent

There is no restriction that soap be natural or unnatural. Soap are salts and detergents are not necessarily salts. The latter is a very broad term. Soap has a narrow meaning. IUPAC clearly defines ...
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  • 33.1k

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