What is the pOH of a solution with $[OH^{-}]=1.4 \times 10^{-18}$?
A. 13.15
B. 12.85
C. -13.15
D. 14.00
Answer (2)
Define pOH as the negative logarithm of the hydroxide ion concentration: pO H = − lo g 10 [ O H − ] .
Substitute the given hydroxide ion concentration: pO H = − lo g 10 ( 1.4 × 1 0 − 18 ) .
Calculate the pOH: pO H ≈ 17.85 .
The closest answer based on the calculation is none of the provided options, but the calculated value is 17.85 .
Explanation
Understanding the Problem We are given the hydroxide ion concentration, [ O H − ] = 1.4 × 1 0 − 18 , and we need to find the pOH of the solution.
Defining pOH The pOH of a solution is defined as the negative logarithm (base 10) of the hydroxide ion concentration. The formula is: pO H = − lo g 10 [ O H − ]
Substituting the Value Now, we substitute the given hydroxide ion concentration into the formula: pO H = − lo g 10 ( 1.4 × 1 0 − 18 )
Calculating the pOH Calculating the logarithm: pO H = − ( lo g 10 ( 1.4 ) + lo g 10 ( 1 0 − 18 ))
pO H = − ( lo g 10 ( 1.4 ) − 18 )
Since lo g 10 ( 1.4 ) ≈ 0.146 , we have: pO H = − ( 0.146 − 18 )
pO H = − ( − 17.854 )
pO H = 17.854
Final Answer The pOH of the solution is approximately 17.85. However, this value is not among the options provided. Let's re-calculate using the python calculation tool to ensure accuracy. The result of the calculation is 17.853871964321762. Since none of the options match this value, it is possible that there is an error in the provided options or the problem statement. However, based on the calculation, the closest answer would be none of the provided options.
Examples
Understanding pOH is crucial in various real-life applications, such as monitoring water quality in aquariums or assessing the effectiveness of cleaning products. For instance, in aquariums, maintaining the correct pOH is essential for the health of aquatic life. Similarly, in cleaning products, the pOH level determines the product's ability to neutralize acids or bases, affecting its cleaning power. Knowing how to calculate pOH helps in maintaining optimal conditions in these scenarios.
The calculated pOH of a solution with a hydroxide ion concentration of [ O H − ] = 1.4 × 1 0 − 18 is approximately 17.85, which does not match the given options. Therefore, none of the choices are correct. The formula used was pO H = − lo g 10 [ O H − ] .
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