Expert: Dr. Henry Boyter, Jr. - 10/10/2004

Question
Dear Dr, Boyter,

I got the folowing question when doing an experiment on acid.

I understand the difference between strong and weak acids and concentrated and dilute acids. But what is the difference between a dilute strong acid and a concentrated weak acid?

Which one is of lower pH? Which one is more corrosive? Which one is more damaging and powerful?

Thanks!

Yours sincerely,
raymond

Answer
A series of questions that can not be answered with the information given.  It all depends on your definition of dilute.  Take the two extremes (1-2).  It also depends on the weak acid (3).

1. If I add one drop of water to 10000 gallons of strong acid, it has been diluted, but you would see no difference in properties.

2. If I diluted a strong acid until there was one molecule of it left in water, it has been diluted, but it would have the properties of plain water.

You can then have everything in between these two extremes depending on the dilution.

3. Remember that water is a weak acid.  In water solutions, dilute strong acids are always at least as strong as the water, no matter how dilute they are.  There are weak acids that are weaker than water.