acids and bases
DESCRIPTION
Acids and Bases. Chapter 14. Some Properties of Acids. Produce H + (as H 3 O + ) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) Taste sour Corrode metals React with bases to form a salt and water pH is less than 7 - PowerPoint PPT PresentationTRANSCRIPT
Some Properties of Acids
Produce H+ (as H3O+) ions in water (the hydronium ion is a
hydrogen ion attached to a water molecule)
Taste sour
Corrode metals
React with bases to form a salt and water
pH is less than 7
Turns blue litmus paper to red “Blue to Red A-CID”
Some Properties of Bases
Produce OHProduce OH-- ions in water ions in water
Taste bitter, chalkyTaste bitter, chalky
Feel soapy, slipperyFeel soapy, slippery
React with acids to form salts and waterReact with acids to form salts and water
pH greater than 7pH greater than 7
Turns red litmus paper to blue “Turns red litmus paper to blue “BBasic asic BBlue”lue”
Acid/Base Definitions
• Brønsted – LowryBrønsted – Lowry
Acids – proton donorAcids – proton donor
Bases – proton acceptorBases – proton acceptor
A “proton” is really just a hydrogen A “proton” is really just a hydrogen atom that has lost it’s electron!atom that has lost it’s electron!
LecturePLUS Timberlake 5
Bronsted-Lowry Acids
Acids are hydrogen ion (H+) donors
Bases are hydrogen ion (H+) acceptors
HCl + H2O H3O+ + Cl-
donor acceptor + -
+ +
Conjugate pairs
acidconjugate
basebase conjugate
acid
An acid and a base which differ only by the presence or absence of a proton (H+ )are called a conjugate acid-base pair. One half of the pair is always on the left-hand side of the equation, the other on the right-hand side.
The stronger an acid, the weaker its conjugate base, and, conversely, the stronger a base, the weaker its conjugate acid.
Example 3.1For each of the following acid/base reactions, link the conjugate acid/base pairs:
a) HCl (aq) + H2O (l) ----> H3O+ (aq) + Cl- (aq)b) H2SO4 (aq) + H2O (l) ----> HSO4
- (aq) + H3O+ (aq)c) NH3 (g) + H2O (l) ----> NH4
+ (aq) + OH- (aq)d) H3O+ (aq) + OH- (aq) -----> 2 H2O (l)
Learning Check!
Ans.
Solutionacid/base base/acid
a) HCl (aq) / Cl- (aq) H2O (l) / H3O+ (aq)b) H2SO4 (aq) / HSO4
- (aq) H2O (l) / H3O+ (aq)c) H2O (l) / OH- (aq) NH3 (g) / NH4
+ (aq)d) H3O+ (aq) / H2O (l) OH- (aq) / H2O (l)
HNO3, HCl, HBr, HI, H2SO4 and HClO4 are the strong acids.
Strong and Weak Acids/BasesStrong and Weak Acids/Bases
The strength of an acid (or base) is determined by the amount of IONIZATION.
The strength of an acid (or base) is determined by the amount of IONIZATION.
STRENGTH OF ACIDS AND BASES
The strength of an acid or base is determined by its percent dissociation/ionization in water.
All strong acids and bases dissociate/ionize completely, 100%.
• Hydrohalic acids: HCl, HBr, HI
• Nitric acid: HNO3
• Sulfuric acid: H2SO4
• Perchloric acid: HClO4
Strong AcidsStrong Acids
• *One of the best known is acetic acid CH*One of the best known is acetic acid CH33COCO22HH
Weak AcidsWeak Acids
•
Common strong bases Common strong bases include include NaOH ,NaOH ,KOH andKOH and Ca(OH)Ca(OH)22..
CaOCaO
Strong BasesStrong Bases
Strong bases areStrong bases are (—OH), oxides of 1A and 2A metals (except Mg and Be), H-, and .
One of the best known weak bases is ammoniaOne of the best known weak bases is ammonia
NHNH3 3 (aq) + H(aq) + H22O (l) O (l) ↔↔ NH NH44+ + (aq) + OH(aq) + OH- - (aq)(aq)
Weak BasesWeak BasesWeak BasesWeak Bases
Polyprotic and amphiprotic
• A polyprotic acid is one which is capable of donating more than one proton.
• A polyprotic base is one which is capable of accepting more than one proton.
• An amphiprotic (amphoteric) substance can act as either an acid or a base.
•