2007-09-30 07:52:17 · 3 answers · asked by hellokittyishottt 1 in Science & Mathematics ➔ Biology
pH = 7
Water has a small tendency to split into hydronium and hydroxide ions. The equation looks like this:
H2O + H2O <--> H3O(+) + OH(-)
Notice that in pure water, the number of hydronium and hydroxide ions is the same.
The pH is calculated by taking the negative logarithm of the hydronium ion concentration:
pH = -log[H3O(+)]
Water autoionizes to such a small extent that its hydronium ion concentration (and also its hydroxide ion concentration) is only 1.0x10^-7 Molar. If you take the negative log of 1.0e-7 M, you get 7.
Adding an acid or a base to water will increase the concentration of hydronium ions (if it's an acid) or hydroxide ions (if it's a base). If the concentration of H3O(+) ions increases, the pH decreases. If the concentration of OH(-) ions increases (causing a decrease in the concentration of H3O(+) ions), the pH increases.
2007-09-30 07:54:40 · answer #1 · answered by Lucas C 7 · 0⤊ 0⤋
At 25 deg C, pH should be 7.
2007-09-30 07:55:29 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋
say what now?!?
2007-09-30 08:01:34 · answer #3 · answered by Anonymous · 0⤊ 0⤋