Strong vs weak acid: - Strong Acid - Will completely ionized. - Meaning will completely break into ions - Weak acid - Will partially ionized - Meaning will sometime break into ions
Strong Base: - Any elements from IA or IIa that forms a compound with hydroxide (OH-) - ex. LiOH - ex. Ca(OH)2
Ionization of water: - involves the transfer of a proton from one water molecule to another to produce a OH- and H3O+ - In pure water only a small amount of OH- and H3O+ at 25 degree C - [H3O+]=[OH-]=1.0x10-7M
Ion- product constant: - Kw is called ion product constant of water. - units are customarily omitted. - Kw=[H3O+][OH-] - Remember that at 25 degree C - [H3O+]=[OH-]=1.0x10-7M - Kw=[1.0x10-7M][1.0x10-7M] - Kw= 1.0x10-14
Kw: - The Kw of water will always be 1.0x10-14. - If you add more [H3O+]or[OH-] the solution will balance out to 1.0x10-14. - What will happen to the [H3O+] when you add HCl? - Answer= the [H3O+] will increase. - Remember acids will always increase[H3O+] - What will happen to the [OH-] when you add HCl? - Answer the [OH-] will go down to balance out to 1.0x10-14
Problem: - What is the concentration of [OH-] if the [H3O+] was 10.0 M? - Kw= [H3O+][OH-] - Kw= 1.0 x 10-14 - 1.0 x 10-14= [10.0M][OH-] - 1.0 x 10-14/10.0= [OH-] - 1.0 x 10-15 M= [OH-]
Understanding Logarithmic function: - Multiplication= short cut for addition - exponential= short cut for multiplication - Logarithmic = short cut for exponential
Calculating pH: - pH=-log [H3O+] - p=-log - so what is the equation of pOH? - answer pOH=-log[OH-] Problems: - What is the pH value for each of the following solution at 25 degree C? - A. A solution in which [H+]=1.00x10-9M - pH=-log [H+] - pH=-log[1.00x10-9] - pH= 9 - What is the pH value for each of the following solution at 25 degree C - A solution in which [OH-]= 1.00 x 10-6M - hint find [H+] - To find [H+], remember Kw= [H+] [OH-] - Kw= 1.0 x 10 -14 - [OH-]= 1.00 x 10-6M - 1.0 x 10 -14= [H+][1.00 x 10-6] - Solve for [H+] - [H+]=1.0x10-8M - Now sub in [H+] in to pH=-log [H+] - pH=-log(1.0x10-8) So pH =8 - What is the pH if the PoH was 8? - pH + pOH=14 - pH+ 8=14 - pH=6 - What is the pH if the [OH] is 3.4 x 10-9 M? - pOH= -log[OH] - pOH=-log(3.4 x 10-9 M) - pOH=8.47 - pH + pOH= 14 - pH + 8.47= 14 - pH=5.53
What is it called with you add an acid and a base together? - Neutralization reaction - one produce will always be water