Can anyone give me a quick chemistry lesson?

[LooL00]

I know (or think) that soap and detergents work by carrying the dirt away in the washing water. And I 'know' that bleach 'kills' stuff (but how?). But how does bicarb or vinegar work, and what do alcohol rubs do that a nice bar of soap doesn't. AND wtf is 'antibacterial' ??
Please educate me.

Bleach is very strong alkali (like acid but the opposite, if that makes any sense!) and it bursts the cells of bacteria, killing them.

Bicarb is a weaker alkali, and vinegar a weak acid - they can both "cut through" grease, so lift greasy/oily dirt off surfaces.

Alcohol rubs - do you mean the ones for hands? They're handy if you don't have any soap, but I don't think they do any more.

And I'm not sure what "antibacterial" means, apart from sounding good on the label

Thanks.So is bicarb strong enough to burst the cells of the bacteria?

I'm not sure about bicarb - I think it would more likely weork by loosing them off the surface, rather than killing them. But tbh I believe in Cif and Bleach rather than the natural products

Alcohols evaporate quickly from your hands so you don't need to use water or dry your hands on a towel (which may contain bacteria).

Vinegar is a weak acid and can be used to remove lime-scale.

Detergents work by using a chemical called a surfactant. This has one end that likes water and another end that doesn't. The surfactant molecules form a "cluster" that mops up dirt in the middle and keeps it suspended in the water so cleaning the clothes.

Alcohol/ethanol acts to kill bacteria as (removes their fats and proteins so zapping them) - so is a sterilising agent. I used to work in a microbiology lab and we always used ethanol spray to clean surfaces. So the alcohol sprays/gels act to kill the bacteria but don't actually 'clean' the dirt - but the dirt at least should be sterile!

(e.g. if you've been on the tube and use the gel afterwards you'll have removed the bacteria (or 99% of them) but would still have bits of grease, snot or whatever from the grimy tube - so still nice to wash your hands with soap and water!!)

Soap and detergents work by popping the bacteria (again protein degradation) through sodium dodecyl/lauryl sulphate sort of thing. And copious water and flushing away helps too.

Antibacterial (or microbicidal) is anything really that slows or kills the growth of bacteria - and it would depend on the active agent about how it does that.

Wow.
I did not know most of that
Thanks brainy MNers

Just as a vaguely medical note. Alcohol gels are ok for cleaning hands when washing is not possible but washing is always preferable if you can. Gels do not kil C Diff which is one of the superbugs the NHS worries about.

Thanks everyone!! So detergent is pretty good stuff (unless you are a bacterium). I noticed (and that's what got me asking questions) that parazone wipes contain ethanol- so they zap bacteria but don't actually help femove any 'debris'.Maybe I should stick to my multi purpose spray (detergent) and loo paper?

zam72 I love this information. Are you Nina? Could I be cheeky and ask another question. When you wash sports clothes at 30 degrees as per labels are you really
a, Killing the germs
b, Killing the smell
c, geting rid of the dirt.

I wish I could wash sports clothes at 6o degrees but silly manaufactures stick to the 30 degress thingy. I don't really want to add eve more chemicals into the wash.
What is your scientific knowledge on these points? Cheers

Hmm....just wondering which of those perky little Neurones should help me now?!

I'd think it the main thing with washing at 30C would be the washing detergent (which will have all the bug zapping components in it and nice smells and stuff to lift off the dirt/grease). Combined with the jiggly action of the washing machine and the copious amounts of water (which many bugs aren't too keen on either) I think washing at 30C should be fine. If you were concerned you could use the newer types of washing liquids that are specifically aimed at low temperature washes as I suppose they've been designed to be effective at 30C and maybe use biological stuff (as I think that uses enzymes that work at lower temps...but that's from a A level chemistry lesson many moons ago...so that could be wrong!).

Sounds good to me. hey! Who said Housework wasn't interesting. I'm might go away and find out more myself. Trouble with big companies I think they LIE! My son has the whites school tops and rugby shorts because I wash them at 60 but I don't think new materail can cope with the temp!

Let us know what you find out starbear. I'm trying make more informed decisions about eco/bleach cleaners. I have both but I'm never sure when bleach is really essential.

The much-missed Martian Bishop once posted this on here - thought you might appreciate it...

A DIALOGUE WITH SARAH, AGED 3: IN WHICH IT IS SHOWN THAT IF YOUR DAD IS A CHEMISTRY PROFESSOR, ASKING ?WHY? CAN BE DANGEROUS
By Stephen McNeil

SARAH: Daddy, were you in the shower?

DAD: Yes, I was in the shower.

SARAH: Why?

DAD: I was dirty. The shower gets me clean.

SARAH: Why?

DAD: Why does the shower get me clean?

SARAH: Yes.

DAD: Because the water washes the dirt away when I use soap.

SARAH: Why?

DAD: Why do I use soap?

SARAH: Yes.

DAD: Because the soap grabs the dirt and lets the water wash it off.

SARAH: Why?

DAD: Why does the soap grab the dirt?

SARAH: Yes.

DAD: Because soap is a surfactant.

SARAH: Why?

DAD: Why is soap a surfactant?

SARAH: Yes.

DAD: That is an EXCELLENT question. Soap is a surfactant because it forms water-soluble micelles that trap the otherwise insoluble dirt and oil particles.

SARAH: Why?

DAD: Why does soap form micelles?

SARAH: Yes.

DAD: Soap molecules are long chains with a polar, hydrophilic head and a non-polar, hydrophobic tail. Can you say ?hydrophilic??

SARAH: Aidrofawwic

DAD: And can you say ?hydrophobic??

SARAH: Aidrofawwic

DAD: Excellent! The word ?hydrophobic? means that it avoids water.

SARAH: Why?

DAD: Why does it mean that?

SARAH: Yes.

DAD: It?s Greek! ?Hydro? means water and ?phobic? means ?fear of?. ?Phobos? is fear. So ?hydrophobic? means ?afraid of water?.

SARAH: Like a monster?

DAD: You mean, like being afraid of a monster?

SARAH: Yes.

DAD: A scary monster, sure. If you were afraid of a monster, a Greek person would say you were gorgophobic.

(pause)

SARAH: (rolls her eyes) I thought we were talking about soap.

DAD: We are talking about soap.

(longish pause)

SARAH: Why?

DAD: Why do the molecules have a hydrophilic head and a hydrophobic tail?

SARAH: Yes.

DAD: Because the C-O bonds in the head are highly polar, and the C-H bonds in the tail are effectively non-polar.

SARAH: Why?

DAD: Because while carbon and hydrogen have almost the same electronegativity, oxygen is far more electronegative, thereby polarizing the C-O bonds.

SARAH: Why?

DAD: Why is oxygen more electronegative than carbon and hydrogen?

SARAH: Yes.

DAD: That?s complicated. There are different answers to that question, depending on whether you?re talking about the Pauling or Mulliken electronegativity scales. The Pauling scale is based on homo- versus heteronuclear bond strength differences, while the Mulliken scale is based on the atomic properties of electron affinity and ionization energy. But it really all comes down to effective nuclear charge. The valence electrons in an oxygen atom have a lower energy than those of a carbon atom, and electrons shared between them are held more tightly to the oxygen, because electrons in an oxygen atom experience a greater nuclear charge and therefore a stronger attraction to the atomic nucleus! Cool, huh?

(pause)

SARAH: I don?t get it.

DAD: That?s OK. Neither do most of my students.

The one thing I'd add on bleach is that, apart from being alkaline, the chlorine saturates double bonds - changes the chemistry. Compounds with lots of double bonds tend to be more colourful, that's essentially why bleach whitens things. But it also disrupts biological molecules, hence kills bugs.

Rusty - that sounds quite like some of the discussions we have on car journeys when DD says to her daddy 'talk about something interesting'.

Other ot topics include sewerage systems and electricity transformers, we don't just do chemistry!

hot topics

That sounds like one of the daily conversations that go on in our house.

If you want to sure that you kill bacteria/viruses at 30 degrees add oxy vanish. For example, most viruses don't die unless you use 65 degrees or higher temperature, but certain detergents (oxy vanish, bleach, etc.) will kill them also at lower temperatures.

Is it just me or do others find it very sad that people in this day and age are so obsessed about killing "germs" on everything including their clothes when they wash them? As long as my clothes are clean I don't care about a few germs - they are everywhere and you can't avoid them. Don't get me started on anti bac sprays for the kitchen etc........

I don't think it is neccessary to "kill all germs around". but my dh's and my sport clothes just smell vile when washed without extra help.
I use dettol liquid disinfectant for that, can only wash them at 30 or they are small enough to dress a doll.

That's why it's nice to know what things actually do bert2e. It seems to me that maybe bleach is only necessary if you need to whiten something and that most cleaning can be done with soap or detergent.

most definately. have never used bleach to clean.

Don't get me started on anti bac sprays for the kitchen etc........

pretty unecessary if you wash your chopping board, knives etc properly.

I met someone researching resistant bacteria who was despairing of triclosan being put into household sprays - apparently its one of the few things left that work against some resistant bacteria (I assume she meant for topical use) and because its sprayed around willy nilly of course bugs were starting to get resistant to that too.

Have to say my pet hate is antibacterial XYZ. I feel it's sort of pointless if you actually thought about the environment around and how many, many bugs there are. Most if which are harmless and some of which are useful.

Personally I use bleach down the loo if it's looking rank. I just use soapy dishwater to clean kitchen surfaces. I am Careful or anal about possible transmission if one of us is sick or squitty but just washing hands etc. antibacterials give a false sense of sterility and are unnecessary and as your friend says not great n terms of encouraging bugs to become resistant.

Thank you for all that info. I hate antibac stuff. I have a cupboard full of chemicals but tend to really only use washing up liquid and hot water. I might never buy a bottle of spray stuff again.
dikkertjedap Thank you for the tip of Dettol and sports clothes.
I would like the following
sports clothes not to smell
white clothes to roughly stay white (note to self must buy more black)
Toilets to look clean
arm pits of clothes not to look brown (bar of soap and a scrub is the only way)
Chopping boards not to smell of onions
Not to give food poison the family. I find the last one works if you throw away the Mayonaise away before 3 month you last used it (never really have it now after the palm oil debate
mirrors not to smear otherwise it better not to bother cleaning!