Dissociation Constant of Water
As a frequently used special case, the dissociation constant of water is often expressed as Kw:
The concentration of water is not included in the definition of Kw, for reasons described in the article equilibrium constant.
The value of Kw varies with temperature, as shown in the table below. This variation must be taken into account when making precise measurements of quantities such as pH.
| Water temperature | Kw / 10−14 | pKw |
|---|---|---|
| 0°C | 0.1 | 14.92 |
| 10°C | 0.3 | 14.52 |
| 18°C | 0.7 | 14.16 |
| 25°C | 1.2 | 13.92 |
| 30°C | 1.8 | 13.75 |
| 50°C | 8.0 | 13.10 |
| 60°C | 12.6 | 12.90 |
| 70°C | 21.2 | 12.67 |
| 80°C | 35 | 12.46 |
| 90°C | 53 | 12.28 |
| 100°C | 73 | 12.14 |
Read more about this topic: Dissociation Constant
Famous quotes containing the words constant and/or water:
“Mr. Clarke played the King all evening as though under constant fear that someone else was about to play the Ace.”
—Eugene Field (1850–1895)
“But the beggar gazes on calamity
And thereafter he belongs to it, to bread
Hard found, and water tasting of misery.”
—Wallace Stevens (1879–1955)