Why 70% Alcohol is a disinfectant not 100%...?

Answer 1

The only point I have to add to the correct answer given above (the first answer) is that alcohol is never present at 100% in the first place. As soon as you open the lid the moisture in the air automatically reduces it to 95%. So there is 70% ethanol and 95% ethanol, but not 100% ethanol.

Furthermore, 70% ethanol is sufficient for a disinfectant, so why waste ethanol?

We don't use full strength bleach either. We could, but we don't because #1 it would cost more, and #2 it's nasty and has bad side effects, so why expose ourselves to that?

Answer 2

The use of 70% alcohol (ethanol) as a disinfectant has nothing to do with being cheaper. 70% ethanol will work as a disinfectant. 100% ethanol will not work as a disinfectant. 100% ethanol will not always kill all the microorganisms while 70% ethanol will. It is not clear why this is true. It may be that 100% ethanol is such a good dessicant that it preserves the microorganisms until water is added and the microorganisms are revived. 70% ethanol does not allow the microorganisms to survive. Note that the disinfecting property is for vegetative cells only, spores may be able to survive either 70% or 100% ethanol.

Answer 3

The previous answer is correct, alcohol on its own tends to fix things to surfaces, by dehydration. By having a 70% solution, it allows a broader range of cleaning, and disinfecting.

Answer 4

Both are, but in the 70% ethanol you´ll be able to dissolve those chemicals and toxins which are water soluble and not alcholol soluble.

Answer 5

because if it's 100% , alcoholics will drink it and get really drunk and disorderly.

haha, just kidding. lovely green eyes is right!

Answer 6

its because its cheaper by being diluted.... and disinfects just as well