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How does pH show whether a solution is acidic or basic?

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sodium sulfate — acid–base reaction Sodium sulfate, also called Glauber's salt, is, like other salts, the product of an acid-base reaction.

The pH scale provides a quantitative measure of the acidity or basicity of an aqueous solution by representing the concentration of hydrogen ions present. It is defined mathematically as the negative logarithm of the hydrogen-ion activity: $pH = - \log_{10} [H_{3} O^{+}]$ .213

On this scale, which typically ranges from 0 to 14, the value of 7 represents neutrality, as seen in pure water. The relationship between pH and the nature of a solution is as follows:42

Acidic: A solution with a pH less than 7 is considered acidic. Higher concentrations of hydrogen ions result in a lower pH value.421
Neutral: A pH of 7 indicates a neutral solution, where the concentration of hydrogen ions is balanced.42
Basic (Alkaline): A solution with a pH greater than 7 is considered basic or alkaline.42

Each unit of change on the pH scale represents a tenfold change in the acidity or alkalinity of the solution. Measurements are commonly obtained using a pH meter, which detects the electrical potential difference between electrodes, or through chemical indicators like litmus paper.52