To analyze the situation accurately, we first need to understand what a pH of 12 means in terms of hydroxide ion concentration ([OH⁻]) and the nature of sodium hydroxide (NaOH).
- pH is a measure of the acidity or basicity of a solution, where pH + pOH = 14.
- A pH of 12 indicates that the solution is basic.
- To find the pOH, you can use the formula pOH = 14 - pH, so: \[ \text{pOH} = 14 - 12 = 2. \]
- The hydroxide ion concentration can be found using the formula \([OH^-] = 10^{-\text{pOH}}\): \[ [OH^-] = 10^{-2} = 0.01 , \text{M}. \]
Now, considering the statements:
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The negative log of the concentration of OH ions is 2. Sodium hydroxide is a strong base.
- This statement is correct as the pOH is indeed 2, and sodium hydroxide is a strong base.
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The negative log of the concentration of OH ions is 2. Sodium hydroxide is a strong acid.
- This statement is incorrect; sodium hydroxide is not an acid.
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The negative log of the concentration of OH ions is 12. Sodium hydroxide is a strong acid.
- This statement is incorrect; it misrepresents the log value related to concentration and is incorrect about the nature of sodium hydroxide.
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The negative log of the concentration of OH ions is 12. Sodium hydroxide is a strong base.
- This statement is also incorrect; the negative log of the concentration of OH ions cannot be 12, given the pOH we calculated.
Therefore, the correct statement is: The negative log of the concentration of OH ions is 2. Sodium hydroxide is a strong base.
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