Write both answers to at least two decimal places. Calculate the pH of a 0.150 M solution of KOH. Calculate the pOH of a 0.150 M solution of KOH.
The Correct Answer and Explanation is:
To calculate the pH and pOH of a 0.150 M solution of KOH (potassium hydroxide), we need to consider the basic nature of KOH, which dissociates completely in water.
Step 1: Understanding the dissociation of KOH
KOH is a strong base, meaning it dissociates completely in water according to the following reaction:KOH→K++OH−\text{KOH} \rightarrow \text{K}^+ + \text{OH}^-KOH→K++OH−
Since KOH dissociates completely, the concentration of hydroxide ions (OH⁻) will be equal to the concentration of KOH. Therefore, in a 0.150 M solution of KOH, the concentration of OH⁻ ions will also be 0.150 M.
Step 2: Calculating pOH
The pOH is calculated using the formula:pOH=−log[OH−]\text{pOH} = -\log[\text{OH}^-]pOH=−log[OH−]
Substituting the concentration of OH⁻:pOH=−log(0.150)=0.82391≈0.82\text{pOH} = -\log(0.150) = 0.82391 \approx 0.82pOH=−log(0.150)=0.82391≈0.82
So, the pOH of the 0.150 M KOH solution is 0.82.
Step 3: Calculating pH
To calculate the pH, we can use the relationship between pH and pOH:pH+pOH=14\text{pH} + \text{pOH} = 14pH+pOH=14
Now, substitute the value of pOH:pH=14−pOH=14−0.82=13.18\text{pH} = 14 – \text{pOH} = 14 – 0.82 = 13.18pH=14−pOH=14−0.82=13.18
Thus, the pH of the 0.150 M KOH solution is 13.18.
Summary:
- pOH = 0.82
- pH = 13.18
Both values are calculated to two decimal places, and these results are consistent with the expected values for a strong base like KOH in this concentration. The pH is very high, reflecting the strong basic nature of the solution, while the pOH is quite low, indicating a high concentration of hydroxide ions.
