pH Acidity Acidic Environment


pH Acidity


pH Acidity
Describing the acidity of a solution using concentrations with negative powers can be cumbersome, so a more convenient approach is to use pH acidity to describe acidity levels.
The pH (potential hydrogen) scale is a logarithmic scale that indicates the concentration of hydrogen ions in a solution.

The higher the concentration of hydrogen ions, the lower the pH is.


pH level
If the pH of a chemical is less than 7, it is an acid. A pH of 7 indicates a neutral substance, and a pH greater than 7 indicates a basic substance. The higher the concentration of hydrogen ions, the lower the pH is.
Because pH is a log scale, a change in pH of 1 indicates a tenfold change in hydrogen ion concentration.
pH can be measured by using indicators or pH meters and probes. Probes and pH meters measure the voltage of the cell formed in a solution and convert it to a pH reading. They are relatively accurate but expensive.
pH meters and indicators tell us the concentration of hydrogen ions in the solution. This depends on the:
• concentration of the solution (how many moles are present in each litre)
• strength of the acid present (how readily they release hydrogen ions)
• number of protons the acid has to donate (hydrochloric acid has 1, sulfuric acid has 2 per molecule)
• temperature of the solution
pH can be measured by using indicators or pH meters and probes.
Probes and pH meters measure the voltage of the cell formed in a solution and convert it to a pH reading.
They are very accurate but expensive.
pH meters and indicators tell us the concentration of hydrogen ions in the solution.
This depends on the:
Concentration of the solution : how many moles are present in each litre.
Strength of the acid : how readily they release hydrogen ions.
Number of protons the acid has to donate. e.g. hydrochloric acid has 1, sulfuric acid has 2 per molecule and is called diprotic.

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