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:
“For centuries the death penalty, often accompanied by barbarous refinements, has been trying to hold crime in check; yet crime persists. Why? Because the instincts that are warring in man are not, as the law claims, constant forces in a state of equilibrium.”
—Albert Camus (1913–1960)
“I respect the ways of old folks, but the blood of a rooster or a goat cannot turn the seasons, change the course of the clouds and fill them up with water like bladders. The other night, at the ceremony for Legba, I danced and sang my fill: I am a black man, no? and I enjoyed it like a true Negro should. When the drums beat, I feel it in the pit of my stomach, I feel the itch in my hips and up and down my legs, I have got to join the party. But that is all.”
—Jacques Roumain (1907–1945)