Presentation on theme: "pH Water Water is in equilibrium with its ions H 2 O(l) H + (aq) + OH - (aq) K w = [H + ][OH - ] K w = 1.0 x 10 -14 at 25°C In neutral solutions [H."— Presentation transcript:
Water Water is in equilibrium with its ions H 2 O(l) H + (aq) + OH - (aq) K w = [H + ][OH - ] K w = 1.0 x 10 -14 at 25°C In neutral solutions [H + ]=[OH - ]= 1x10 -7 If [H + ]>[OH - ], solution is acidic If [H + ]<[OH - ], solution is basic
Example Find the [H + ] if a) [OH - ]=.010M b) [OH - ]= 2.0 x 10 -9 M
pH Very small numbers can be conveniently expressed on a log scale pH = -log [H + ] pH = 7, neutral pH < 7, acidic pH > 7, basic
Example Calculate the pH of lemon juice with an [H + ]= 3.8 x 10 -4 M Calculate the pH of window cleaner with an [H + ]= 5.3 x 10 -9 M What is the [H + ] of apple juice with a pH of 3.76.
Indicators Used to estimate pH Colored substance that exists in either acid or base form Acid and base form are different colors By knowing the pH where it changes color, we can determine its relative pH