What is the ionic product of water?
Even pure water slightly splits into H⁺ and OH⁻. K_w is the product of their concentrations, fixed at about 10⁻¹⁴ at 25°C, locking the two ions together.
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Ionic Product of Water (K_w)
Calculate K_w = [H⁺][OH⁻] (=10⁻¹⁴ at 25°C), with symbol legend and real-world examples.
Kw = [H^+][OH^-] = 10⁻¹⁴
Frequently asked questions
Why is it important?
Knowing one ion gives the other, since the product is fixed. It underlies the whole pH scale and links acidity to basicity.
Why is neutral water pH 7?
In pure water H⁺ = OH⁻, and since their product is 10⁻¹⁴ each is 10⁻⁷, giving pH 7 - the natural midpoint.
Does K_w change with temperature?
Yes - water ionises more when warm, so K_w rises and neutral pH dips slightly below 7 in hot water. The '7 = neutral' rule is for 25°C.
How does the example give 10⁻¹⁴?
[H⁺] = 10⁻⁷ and [OH⁻] = 10⁻⁷ multiply to 10⁻¹⁴ - exactly the value for neutral water.