How can we help?

You can also find more resources in our Help Center.

23 terms

LC Chem 9.1 pH

chemistry
STUDY
PLAY
Kw
The ionic product of water = [H+][OH-]
1 x10^-14
= [H+] [OH-] at 25°C
Increases
Change in Kw with increasing temperature.
pH scale
Measures the concentration of hydrogen ions in solution
pH
= log10[H+] where the square brackets indicate concentration in moles per litre.
[H+]
= 10^-pH
pOH
= - log10[OH-]
[OH-]
= 10^-pOH
14
= pH + pOH
Ka
The acid dissociation constant (an accurate measure of the extent to which an acid dissociates) = [H+] [A-] / [HA]
Strong
Acids which have relatively large values of Ka (>10^-2)
Weak
Acids which have small values of Ka (<10^-2)
Kb
The base dissociation constant (an accurate measure of the extent to which a base dissociates)
pH (weak acid)
= -log10 √(Ka x M)
pOH (weak base)
= -log10 √(Kb x M)
Methyl Orange
Indicator for Strong Acid - Weak Base Titration
Phenolphthalein
Indicator for Weak Acid - Strong Base Titration
3.1 - 4.4
pH range in which Methyl Orange changes colour
Red
Colour of Methyl Orange in Acid
Yellow
Colour of Methyl Orange in Base
8.3 - 10
pH range in which Phenolphthalein changes colour
Colourless
Colour of Phenolphthalein in Acid
Pink
Colour of Phenolphthalein in Base