How to find hydroxide ion concentration from pH?
Understand the Problem
The question is asking how to calculate the hydroxide ion concentration from a given pH value. It involves understanding the relationship between pH and the concentration of hydroxide ions, which is typically calculated using the formula: [OH⁻] = 10^(14 - pH).
Answer
The hydroxide ion concentration is $1 \times 10^{7} \, \text{mol/L}$.
Answer for screen readers
The hydroxide ion concentration at a pH of 7 is $1 \times 10^{7} , \text{mol/L}$.
Steps to Solve
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Identify the pH value Determine the given pH value. For example, let's say the pH value is 7.
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Use the formula for hydroxide ion concentration The formula to calculate the hydroxide ion concentration from pH is given by:
$$ [OH⁻] = 10^{14 - pH} $$
- Substitute the pH value into the formula Using the given pH value of 7, we substitute into the formula:
$$ [OH⁻] = 10^{14 - 7} $$
- Calculate the exponent Perform the subtraction in the exponent:
$$ [OH⁻] = 10^{7} $$
- Calculate the hydroxide ion concentration Finally, compute the value:
$$ [OH⁻] = 10000000 \text{ or } 1 \times 10^{7} , \text{mol/L} $$
The hydroxide ion concentration at a pH of 7 is $1 \times 10^{7} , \text{mol/L}$.
More Information
At a neutral pH of 7, the concentration of hydroxide ions is equal to the concentration of hydrogen ions, which is also $1 \times 10^{7} , \text{mol/L}$. This is an important concept in acid-base chemistry.
Tips
- Forgetting to subtract the pH value from 14 in the exponent of the formula. Always remember the correct formula is $[OH⁻] = 10^{14 - pH}$.
