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What is the principle behind the pH scale?
Jan 3, 2024
What is the principle behind the pH scale?
Here is your solution: #Step 1#
The pH scale is a measure of the acidity or basicity of an aqueous solution. It is based on the concentration of hydrogen ions (H+H^+) in the solution.
#Step 2#
The pH is defined as the negative logarithm (base 10) of the hydrogen ion concentration: pH=−log⁡[H+] pH = -\log[H^+] where [H+][H^+] is the concentration of hydrogen ions in moles per liter (M).
#Step 3#
A pH of 7 is considered neutral, which is the pH of pure water at 25°C. Solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic (alkaline).
#Step 4#
The pH scale typically ranges from 0 to 14, with each unit representing a tenfold difference in hydrogen ion concentration. For example, a solution with a pH of 4 has ten times more hydrogen ions than a solution with a pH of 5.
Answer
The principle behind the pH scale is the measurement of the hydrogen ion concentration in a solution, which is expressed as the negative logarithm of its value.
Key Concept
pH Scale and Hydrogen Ion Concentration
Explanation
The pH scale quantifies the acidity or basicity of a solution based on the concentration of hydrogen ions present, using a logarithmic scale where a lower pH indicates higher acidity and a higher pH indicates higher basicity.
What is the formula to calculate pH?
Here is your solution: #Step 1#
The pH of a solution is a measure of its acidity or alkalinity, which is based on the concentration of hydrogen ions (H+H^+) present. The formula to calculate pH is derived from the concentration of hydrogen ions in the solution.
#Step 2#
The pH is calculated using the negative logarithm (base 10) of the hydrogen ion concentration. The formula is: pH=−log⁡[H+] pH = -\log[H^+] where [H+][H^+] is the concentration of hydrogen ions in moles per liter (M).
#Step 3#
If the concentration of hydrogen ions is given, you can directly apply the formula. If you have the concentration of a strong acid or base, you can assume that it dissociates completely and use its concentration as [H+][H^+] or [OH−][OH^-] accordingly. For weak acids or bases, you would need to calculate the [H+][H^+] using an equilibrium expression.
Answer
The formula to calculate pH is: pH=−log⁡[H+] pH = -\log[H^+]
Key Concept
pH calculation
Explanation
pH is calculated using the negative logarithm of the hydrogen ion concentration in the solution.
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