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Guilherme Mazui

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What is the Difference Between pH and Acidity?

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The main difference between pH and acidity lies in their definitions and the scale used to measure them.

  • pH: It is a scale used to express the degree of acidity or basicity (alkalinity) of an aqueous solution. The pH scale ranges from 0 to 14, with 7 being neutral. A pH value below 7 indicates acidity, while a value above 7 indicates a basic solution. PH is a logarithmic measure of the concentration of free hydrogen ions (H+) and hydroxide ions (OH-) in a solution. For example, a pH value of 5 is ten times more acidic than a pH value of 6.
  • Acidity: It refers to the concentration of hydrogen ions (H+) in an aqueous solution. When the concentration of hydrogen ions is high, the solution is acidic. In contrast, when the concentration of hydrogen ions is low, the solution is basic or alkaline.

While pH is the scale used to express acidity, it is not synonymous with acidity itself. Acidity is the actual concentration of hydrogen ions in a solution, while pH is a logarithmic measure of the relative amount of free hydrogen and hydroxyl ions in the water. In summary, pH is a scale used to quantify the acidity or basicity of a solution, while acidity refers to the actual concentration of hydrogen ions in the solution.

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  • What is the Difference Between pH and Acidity?
  • Comparative Table: pH vs Acidity

    • Comparative Table: pH vs Acidity

    The difference between pH and acidity can be summarized in the following table:

    Feature pH Acidity
    Definition pH is a measure of the concentration of hydrogen ions (H+) in a solution. It is a logarithmic measure with a range of 0 to 14, where 7 is neutral, less than 7 indicates acidity, and greater than 7 indicates alkalinity (basicity). Acidity refers to the amount of hydrogen ions (H+) present in a solution. It is a broader term that can be quantified using pH values.
    Measurement pH values are obtained using a logarithmic scale, with each number representing a 10-fold change in acidity or basicity. Acidity can be inferred from pH values, but it is not directly measured. Acidity is indirectly measured by determining the pH of a solution and comparing it to the pH scale.
    Examples - Pure water (pH 7): Neutral
    - Lemon juice (pH 2): Acidic
    - Baking soda (pH 9): Basic    		 - Acidic: Lemon juice, vinegar, gastric acid
    - Neutral: Pure water
    - Basic: Baking soda, soapy water, bleach

    In summary, pH is a logarithmic measure of the concentration of hydrogen ions in a solution, while acidity refers to the amount of hydrogen ions present. Acidity can be quantified using pH values, but it is not directly measured.

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    Guilherme Mazui

    Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.