To analyze the information given, we need to understand the relationship between pH, pOH, and the concentration of hydroxide ions (\(OH^–\)).
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When the pH of a solution is 12, we can find the pOH using the relationship: \[ pH + pOH = 14 \] Thus: \[ pOH = 14 - pH = 14 - 12 = 2 \]
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The concentration of hydroxide ions (\(OH^–\)) can be calculated from the pOH: \[ pOH = -\log[OH^-] \] Rearranging gives: \[ [OH^-] = 10^{-pOH} = 10^{-2} = 0.01 \text{ M} \]
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Now, considering the nature of sodium hydroxide (NaOH):
- Sodium hydroxide is a strong base and dissociates completely in water, producing hydroxide ions (\(OH^–\)).
- The presence of a high concentration of \(OH^–\) (0.01 M in this case) and a corresponding high pH (12) confirms that it is indeed a strong base.
Now, let's evaluate each of the response statements based on these calculations:
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“The negative log of the concentration of \(OH^–\) ions is 2. Sodium hydroxide is a strong base.” - This is correct. The pOH is 2 and indicates 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 is incorrect. Sodium hydroxide is a strong base, not a strong acid.
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“The negative log of the concentration of \(OH^–\) ions is 12. Sodium hydroxide is a strong base.” - This is incorrect. The negative log of the concentration of \(OH^–\) ions is 2, not 12.
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“The negative log of the concentration of \(OH^–\) ions is 12. Sodium hydroxide is a strong acid.” - This is also incorrect. Again, the log value is not 12, and sodium hydroxide is a strong base.
Conclusion: The only correct statement is the first one: "The negative log of the concentration of \(OH^–\) ions is 2. Sodium hydroxide is a strong base."