what is the difference between a strong acid and a weak acid?

Answer 1

Acidity is to do with H+ ions. Some acids will completely break up into its ions, so imagine if it was HCl, every molecule might become H+ and Cl-, rather than staying as the complete HCl molecule. That would be a strong acid. If it was a weak acid, it means only a few of the molecules break up into its ions and most of them stay as the whole molecule.

Answer 2

This six strong acids are HCl (hydrochloric acid), HBr (hydrobromic acid), HI (hydroiodic acid), HClO4 (perchloric acid),
HNO3 (nitric acid), and H2SO4 (sufuric acid). They are considered strong acids because they almost completely dissociate (break up) in water. All other acids are considered weak acids.

Acids don't actually have to contain Hydrogen however, they only have to accept an electron pair in reaction. So a more accurate measure of the strength of an acid is its pKA, which is the negative log of the Ka or dissociation constant of an acid in an aqueous solution. A stronger acid will have a lower pKa value. Also, another way of measuring the strength of an acid is is by the strength of its conjugate base. A strong acid will produce a weak conjugate base and a weak acid will produce a strong conjugate base.

Answer 3

strong and weak has nothing to do with pH although pH varies with acid strength. Strong acids are completely ionised in water and weak ones are only partially ionised. For example hydrochloric acid in water exists as coordinated Cl- ions and H3O+ ions (free protons don't occur). pH is a value pH=-log([H+]) (the negative logarithim of the hydrogen ion species concentration in solution) and so a dilute solution of a strong acid will have a lower hydrogen ion species concentration than a concentrated one but is still a strong acid. For examples HCl is a strong acid and acetic acid is a weak one.

Adding this-the pH scale applies to bases as well because pure water has an H+ concentration of 10e-7, add OH- and H+ are used to make H2O and so H+ concentraion goes down pH=log([H+]) so say it goes down to 10e-12 we have pH=-log(10e-12)=-(-12)=12 and the product of H+ and OH- is always 10e-14 to maintain the equilibrium

Answer 4

Well if you get a strong acid poured on you it takes seconds/split seconds to burn your skin/tissue if you come into contact with a very weak acid it may cause some light irritation...
the ph scale defines between acid and alkaline solutions you should look this up for your answer.....

Answer 5

1. a strong acid is an acid that dissociates completely in aqueous solution

e.g. HCl --> H+ + Cl-

The solution will consist of hydrogen ions and chlorine ions and there will not be any completel molecules of HCl remaining.
here is a list and a reference
http://en.wikipedia.org/wiki/Strong_acid

2. A weak acid is an acid which does NOT completely dissociated in aqueous solution.

an example is acetic acid

CH3COOH <-----> CH3COO- + H+

There will always be a portion of the original molecule in the solution.

here is a reference
http://en.wikipedia.org/wiki/Weak_acid

Answer 6

A strong acid is one which is virtually 100% ionised in solution.They have pH values between 1 and 2 generally, and weak acids have pH values of around 4-6. A weak acid is partially ionized in solution. e.g. ethanoic acid: CH3COOH +H2O ---------> CH3COO + H3O AS you can see, it still retains hydrogen in its formula after the reaction is complete

Answer 7

zebbedee has given a fantastic answer. His first paragraph is pretty much exactly what is taught at the start of A level chemistry, so please ignore all the people who are saying strong acids have a low pH.

A strong acid has more dissociation, a concentrated acid has a low pH.

Answer 8

The difference is the Ph. I higher acidity has a lower Ph, that's why Water is like 7, it's right in the middle between acidic and basic.

Answer 9

A strong acid is completely ionised when dissolved in water. They include hydrochloric acid, sulphuric acid and nitric acid. Their PHs range from 0 to 2. Strong acids are INORGANIC.

A weak acid is one that is partially ionised when dissolved in water. They include carbonic acid, ethanoic acid, phosphoric acid etc.......their PHs range from 3 to 6. Weak acids are generally ORGANIC.

Answer 10

a strong acid has a lower pH whereas a weak acid has a higher pH.
strong acids turn universal indicator red or dark orange, and weak acids would turn UI light orange or possibly yellowy orange