26

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 molecule would be a (generally sodium) salt of butyric (butanoic) acid, i.e. sodium butyrate. Now apart from the chemical definition, a soap must adhere to its ...


18

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 better understand the mode of action, you have to know a bit about the formulation of shampoos and the nature of dirt and oils. Dirts and oils deposit on hair ...


14

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 is generated because surfactants in the detergent adsorb at the air water interface and stop the water film that makes up the walls of the bubbles from ...


14

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 the logic behind the English equivalent surfactant is just the same. So, in summary tensid and surfactant mean the same.


11

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 participate Alkaline precipitation of $\ce{Cu(OH)2}$ in the neutrally-buffered soap Insufficient $\ce{Na_4EDTA}$ to complex the amount of $\ce{Cu}$ corroded from ...


10

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 with a single parameter. Quoting Ref. 1 : Detergency is difficult to evaluate because it depends on a multitude of variables that in most cases are ...


7

The diazo dye (1), known as Solvent Yellow 124 or Somalia Yellow is soluble in aliphatic hydrocarbons. In the European Community, it is used to mark low-taxed diesel fuel (for heating purposes). In order to prevent its use in cars, samples are acidified. This results in acetal cleavage and protonation of the diazo-fragment, yielding the red, water-soluble ...


7

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 derivatives. The examples you found by googling are in this class. 3,5-dimethyl-1-hexyn-3-ol is the principal component of Surfynol 61 (probably named Surfynol ...


7

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 that are not fatty acid salts. I also do not think that soap and surfactant are interchangeable words. Surfactants lower surface tension, soaps create micelles ...


7

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 scientifically meaningless because it will be an umbrella term. Just like the term polarity is misused, soapiness could be even worse. The only common property of ...


6

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 gas-phase molecules do not chemically affect the surface tension of liquids. I know its a broad question, so for example, are there any gases that could reduce ...


6

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 water softener is installed on water distribution.


5

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 excess SLS.


5

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 dust inside will be more likely to make contact with the liquid surface of the bubble within the lifetime of the bubble. Also, when it does make contact, it will ...


5

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 degraded by loss of one carbon atom at a time (α-oxidation). * text by the authors, highlighting and hyperlinking by me. A study by Whyte et al2 on the degradation ...


4

The micellization releases water molecules which initially solvate the hydrophilic head groups. The release of these waters greatly increases the entropy. Reference: Dong et al., Chem. Rev. 2010, 110, 4978-5022.


4

CTAB, aka Hexadecyltrimethylammonium bromide DTAB, aka Dodecyltrimethylammonium bromide Sort of a vague question, don't know where to start. To begin, CTAB has a hydrocarbon chain length of 16 (as its name suggests) whereas DTAB has a -CH2- chain length of 12. Otherwise they have the same hydrophilic/polar "head"; all this is obvious, you can tell just by ...


4

I'm afraid no: you are applying a chemical principle to a complex biological response. The Le Chatelier principle state: If a chemical system at equilibrium experiences a change in concentration, temperature, volume, or partial pressure, then the equilibrium shifts to counteract the imposed change and a new equilibrium is established. We start with the ...


4

Can I wash my hair with dishwashing agent [...]! If it's an agent for dishwashing machines: Please DON'T! Cleaning in dishwashing machines is performed in alkaline medium. The tabs usually contain (among others): alkaline compounds, such as sodium carbonate and sodium hydroxide bleaching agents, such as sodium perborate and sodium percarbonate ...


4

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 the surfactants in the soap that make the foam might be forming micelles around whatever grime is in your sponge, so that there aren't many left to make the ...


4

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 detergents and laundry detergents. It does seem more convenient to use a liquid detergent for washing dishes in the sink. A liquid doesn't need time to ...


4

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 of "agitation" uses the example of washing. From Vocabulary.com Agitation is the act of stirring things up, like the agitation of a washing machine that ...


4

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 temperature (before surfactants) and then homogenised (once thickening agents, if any, have been added). The other thing which may help is by dissolving in denatured ...


4

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.


4

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. Yakhmi, Langmuir, 2000, 16 (18), pp 7187–7191, DOI: 10.1021/la000517o). Additionally, there are cationic micelle detergents (Ionization of cationic micelles: ...


4

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 mixture of tiny salt crystals formed, and water might be responsible for a greasy sensation.


3

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 textile surfaces". This is in the book "Laundry Detergents" written by E. Smulders. There is a whole chapter on the physical chemistry of the washing process. You ...


3

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. The oil actually dissolves the styrofoam. The oil acts a defoamer. So with a styrofoam cup you're suppose to use "commercial" lemon juice which has no oil (lest ...


Only top voted, non community-wiki answers of a minimum length are eligible