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A small amount of sodium hydroxide is added to water. When the chemical reaction reaches equilibrium, the pH is 12. Which statement and conclusion about sodium hydroxide is correct?(1 point) Responses The negative log of the concentration of OH– ions is 2. Sodium hydroxide is a strong acid. The negative log of the concentration of OH – ions is 2. Sodium hydroxide is a strong acid. The negative log of the concentration of OH– ions is 12. Sodium hydroxide is a strong acid. The negative log of the concentration of OH – ions is 12. Sodium hydroxide is a strong acid. The negative log of the concentration of OH– ions is 12. Sodium hydroxide is a strong base. The negative log of the concentration of OH – ions is 12. Sodium hydroxide is a strong base. The negative log of the concentration of OH– ions is 2. Sodium hydroxide is a strong base.

1 answer

To determine the correct statement and conclusion about sodium hydroxide based on the given information, let's analyze the situation:

  1. When sodium hydroxide (NaOH), a strong base, is dissolved in water, it dissociates completely to produce hydroxide ions (OH⁻).

  2. A pH of 12 indicates a basic solution. The relationship between pH and pOH can be established using the following equations:

    • pH + pOH = 14

    From this, you can calculate the pOH:

    • pOH = 14 - pH
    • pOH = 14 - 12 = 2

  3. The concentration of hydroxide ions ([OH⁻]) can be determined from the pOH. Since pOH is defined as:

    • pOH = -log[OH⁻]

    Rearranging gives:

    • [OH⁻] = 10^(-pOH) = 10^(-2) = 0.01 M

Now let's evaluate the options provided:

  • The negative log of the concentration of OH⁻ ions is 2. Sodium hydroxide is a strong acid.
  • The negative log of the concentration of OH⁻ ions is 12. Sodium hydroxide is a strong acid.
  • The negative log of the concentration of OH⁻ ions is 12. Sodium hydroxide is a strong base.
  • The negative log of the concentration of OH⁻ ions is 12. Sodium hydroxide is a strong base.
  • The negative log of the concentration of OH⁻ ions is 2. Sodium hydroxide is a strong base.

From the calculations above, we established that:

  • The pOH is 2 (not 12).
  • The concentration of OH⁻ ions corresponds to that pOH value, confirming that sodium hydroxide is indeed a strong base.

Therefore, the correct statement is:

"The negative log of the concentration of OH⁻ ions is 2. Sodium hydroxide is a strong base."