Calculate The Ph of 0.075m Koh at The Following Temperatures
'/%3E%3Ccircle cx='48' cy='39' r='19' fill='%23f2c9a5'/%3E%3Cpath d='M27 35c3-16 39-17 42 2-8-8-27-9-42-2z' fill='%23374151'/%3E%3Cpath d='M21 86c5-24 49-28 56 0z' fill='%232563eb'/%3E%3Ccircle cx='41' cy='41' r='2' fill='%23111827'/%3E%3Ccircle cx='55' cy='41' r='2' fill='%23111827'/%3E%3Cpath d='M42 52c4 3 9 3 13 0' stroke='%2392400e' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E)
Reviewed by Calculator Editorial Team
This calculator helps determine the pH of a 0.075 molar potassium hydroxide (KOH) solution at various temperatures. The pH of a strong base solution depends on both the concentration of the base and the temperature of the solution.
Introduction
Potassium hydroxide (KOH) is a strong base that completely dissociates in water to form K⁺ and OH⁻ ions. The pH of a KOH solution can be calculated using the following relationship:
For a strong base like KOH, the concentration of OH⁻ ions is equal to the concentration of the base. The temperature affects the dissociation constant of water (Kw), which in turn affects the pOH value.
How to Use This Calculator
- Enter the concentration of KOH in molarity (M). The default is 0.075 M.
- Select the temperature at which you want to calculate the pH. Options range from 0°C to 100°C.
- Click "Calculate" to see the pH result.
- View the result and interpretation guidance.
The calculator uses the temperature-dependent dissociation constant of water (Kw) to provide accurate pH values.
Formula Used
The pH of a KOH solution is calculated using the following steps:
- Determine the concentration of OH⁻ ions: [OH⁻] = [KOH] = 0.075 M
- Calculate pOH: pOH = -log[OH⁻]
- Calculate pH: pH = 14 - pOH
The temperature affects the value of Kw, which is used to adjust the pOH calculation. The calculator uses the following temperature-dependent Kw values:
| Temperature (°C) | Kw (mol²/L²) |
|---|---|
| 0 | 1.16 × 10⁻¹⁵ |
| 10 | 1.43 × 10⁻¹⁵ |
| 20 | 1.81 × 10⁻¹⁵ |
| 30 | 2.34 × 10⁻¹⁵ |
| 40 | 3.05 × 10⁻¹⁵ |
| 50 | 3.98 × 10⁻¹⁵ |
| 60 | 5.18 × 10⁻¹⁵ |
| 70 | 6.70 × 10⁻¹⁵ |
| 80 | 8.60 × 10⁻¹⁵ |
| 90 | 1.10 × 10⁻¹⁴ |
| 100 | 1.40 × 10⁻¹⁴ |
Worked Example
Let's calculate the pH of 0.075 M KOH at 25°C:
- Given: [KOH] = 0.075 M, Temperature = 25°C
- At 25°C, Kw = 1.0 × 10⁻¹⁴
- [OH⁻] = [KOH] = 0.075 M
- pOH = -log(0.075) = 1.122
- pH = 14 - pOH = 14 - 1.122 = 12.878
The pH of this solution is approximately 12.88.
Interpreting Results
The pH of a KOH solution is typically between 12 and 14, indicating a strongly alkaline solution. The exact pH depends on:
- The concentration of KOH
- The temperature of the solution
- The dissociation constant of water at that temperature
Higher temperatures generally result in slightly higher pH values due to the increased Kw value.
FAQ
- Why does temperature affect the pH of KOH?
- Temperature affects the dissociation constant of water (Kw), which in turn affects the pOH calculation. Higher temperatures increase Kw, resulting in slightly higher pH values.
- Can this calculator be used for other strong bases?
- Yes, the same principles apply to other strong bases like NaOH. The calculator can be adapted for those cases by changing the base concentration.
- What is the pH of a neutral solution?
- A neutral solution has a pH of 7 at 25°C. Strong bases like KOH will always have a pH greater than 7.
- How accurate are the temperature-dependent Kw values?
- The Kw values used in this calculator are standard values for pure water. For more precise calculations, you may need to use experimentally determined Kw values for your specific solution.