What is negative ph?

Question

I was reading an article about the negative effects that mining has on the environment, and it was mentioned that the waste waters often had negative ph! How is this possible?

Ten points to the first correct answer! Please put it in layman's terms for me...I'm an accounting clerk, not a chemist ;)

Answer 1

pH of a solution is an indication of the concentration of any dissolved substance in the solution. the lower the pH, the greater the concentration of the dissolved substance, and the higher the pH, the lower the concentration of the substance(NOTE THAT THIS IS IN REFERENCE TO SEWERS AND INDUSTRIAL WASTE LIKE YOU HAVE MENTIONED AND NOT A GENERAL THEORY) the pH is actually an indicator of the concentration of the hydrogen ions in the solution
the pH is calculated as the negative of the logarithm of the concentration of the hydrogen ions(which indicates the concentration of the acid)
now if the concentration of the acid is more, the concentration of hydrogen ions is more which means that the pH is more
now if the concentration of acid is more, then pH may become negative as the logarithmic value is positive
hence the writer has only wanted to say that the waste waters were more of concentrated acids than water

Answer 2

Negative Ph

Answer 3

Can Ph Be Negative

Answer 4

The common definition of pH given in General Chemistry textbooks is really an approximation, not an equation; namely, the 'equation' pH = -log[H3O+] = -log[H+] works in most but not all cases. The pH of any solution, according to this 'equation', will seem negative whenever [H+] > 1, because the common logarithm of any number greater than one is positive. For example, if pH = 0, then [H+] = 10^(-1)(0) = 10^(0) = 1 M. And if pH = -1.00, then [H+] = 10^(-1)(pH) = 10^(-1)(-1) = 10 M. Now if pH = -2.00, then [H+] = 100 M! Finally, if the pH of the mine water in Iron Mountain, California really were -3.6, then the concentration of hydrogen ions in this water would be 10^(-1)(-3.6) = 10^(3.6) = 3 981 M!! Obviously, something is wrong with the high school definition.

High school students, and college freshman are, in general, not allowed to use such concentrated solutions of strong acids. So, they are taught that pH = -log[H+] because it works for the solutions that they are allowed to handle.

The complete definition of pH is easy to show but rather abstruse and often difficult to calculate without Excel. The summary is this: when we measure pH with a pH meter (glass electrode), we are measuring the negative logarithm of the hydrogen ion ACTIVITY, not its concentration; namely, pH = -log ( [H+]*a ), where 0 < a <= 1. The letter 'a' represents the "activity coefficient"; it remains greater than zero because the logarithm of zero is undefined; and it remains less than one because the activity (apparent concentration) of any ion is always less than or equal to the real concentration of the ion. In other words, the high school definition assumes that a = 1.

The process of figuring out the correct value for the activity coefficient in various circumstances is so laborious that the complete definition is, in general, not taught until one takes a course in Quantitative Analysis or Instrumental Analysis as a junior in college.

Consult chapter 8, called Activity, in "Quantitative Chemical Analysis" (6e) written by Daniel C. Harris for all the details.

By the way, mining not only acidifies ground water but also rain. The pH of the most acidic rain ever measured in the USA was obtained at Wheeling, West Virginia. It was 1.7! That's more acidic than pure lemon juice (pH = 2.3)!

Answer 5

A negative pH indicates a very strong concentrated acid.

The pH is the -log(10) of the hydrogen ion concentration, so for H+ ion concentrations greater than 1 mole per liter, the pH would be negative.

Answer 6

The PH scale is a measurement of the number of extra, or missing hydrogen atoms in a chemical compond. We use it to determine how strong an acid is.

Acids when exposed to other substances steal their hydrogen atoms, this is commonly called acid burn.

Chemicals with a negative PH have extra hydrogen atoms, these are known as Bases. When a basic chemical is exposed to a substance, it adds its extra hydrogen atoms to it. Although it does not seem like it, this is just as (if not more) dangerous as acid burn.

A classic example of a basic substance would be common household baking soda, that you keep in your fridge. I makes the inside of your fridge smell clean because any floating "stink" particles that come in contact with the box get burnt up by the soda. Vinegar, an acid would have a similar effect, but because it is a liquid, it would evaportate if you left it in an open bottle for too long.

Answer 7

This Site Might Help You.

RE:
What is negative ph?
I was reading an article about the negative effects that mining has on the environment, and it was mentioned that the waste waters often had negative ph! How is this possible?

Ten points to the first correct answer! Please put it in layman's terms for me...I'm an accounting clerk, not a...

Answer 8

Nowadays extremely strong acids may be synthesized. If you measure there pH its found to be negative. It means that its even stronger than sulfuric acid itself.
pH= -log (concentration of hydrogen ion in the solution).
If this concentration is extremely high like in some types of sulfonic acids then you get a negative result in the definition equation!

Answer 9

The is no such thing as negative pH. pH is measured on a scale of 0 - 14. The article may have meant that the pH is negative such as having a negative affect.

Answer 10

Even concentrated sulfuric acid has a negative pH. It will burn you that bad, I have a scar on my arm to prove it, albeit a small one