Weak acids and bases I - Lecture 5 Flashcards
3 types of reactions
*Precipitation
*Electron transfer (oxidation)
*Acid-base
Lewis definition
Lewis Acid is an e- pair Acceptor
Lewis base is an e- pair donor
What is a dative/coordinate bond?
When one molecule gives away their e- PAIR to form a covalent bond with another
Bronsted - Lowry
Acid is a proton donor (gives to e- pair to form a bond)
Base is a proton acceptor
Distinct feature of a conjugate acid-base reaction
Forms conjugate acid - base pairs that differ only by an electron
What does conjugate base mean?
An acid that has donated a proton to become more negative
What makes a base?
Needs to be a proton acceptor so need to have at least one lone pair and produced through DEPROTONATION
What is the constant for water?
The ionisation constant Kw
Why is it written as H3O+ and not just H+?
Because H+ is a very polarising ion and will from H3O+ quickly, so to be accurate we use H3O+
How to quantify conc. of H3O+ ions?
Use pH = -log[H3O+]
How to find conc. of H3O+ from pH?
[H3O+] = 10ˆ-pH
What is pOH?
-log[OH-]
pKw = ?
pH + pOH = 14
How does temperature affect the Kw?
As temp increases, the Kw increases as more ions get dissociated.
What are strong acids?
Acids that undergo complete dissociation in water i.e they give all their protons away
