Acids and Bases Introduction Acids and Bases are
Acids and Bases
Introduction Acids and Bases are compounds that have special properties and characteristics. n They are not always liquids you see on TV that eat through anything. n Acids and bases are molecular compounds dissolved in water. n
Comparisons Acid Common Properties n Soluble in water n Tastes sour n Turns blue litmus paper red Common Reactions n Base Soluble in water n. Tastes bitter n Feels slippery n Turns red litmus paper blue n Reacts with metals n Reacts with in single displacement organic compounds and reactions to produce breaks them up hydrogen gas n Reacts with carbonate ions to release carbon dioxide gas
Comparisons Acid Chemical Make-Up n Examples n Base Releases Hydrogen n Releases Hydroxide ions in water (H+) ions in water (OH) n Always contains n Usually contains Hydrogen either hydroxide or bicarbonate Hydrochloric acid (HCl) n Vinegar – Acetic acid n Carbonic acid – in soft drinks Baking Soda – Sodium Bicarbonate n Sodium Hydroxide – Drain cleaner n
Naming Common Acids n 2 most important classes of acids: n Binary Acids: Hydrogen bonded with a single non-metal element. n Named according to the element bonded with Hydrogen Ex: HF(aq) = Hydrofluoric Acid, H 2 S(aq) = Hydrosulphuric Acid n Oxyacids: Hydrogen bonded with polyatomic compounds. n Named according to the polyatomic ion bonded with Hydrogen, however it is not as systematic as binary acids. Ex: H 2 SO 4(aq) = Sulphuric Acid, HNO 3(aq) = Nitric Acid
The p. H Scale Solutions are classified on the p. H (power of Hydrogen) scale which describes how acidic or basic it is. n Pure water has a p. H of 7 (neutral). n Substances with a p. H below 7 are Acidic. n Substances with a p. H above 7 are Basic. n p. H = -log 10 [H+] n
The p. H Scale The p. H scale is a logarithmic scale. n Every change of 1 on the p. H scale represents a 10 -fold effect in the concentration. n Ex: p. H of 2 is 10 X more acidic than a p. H of 3. n p. H of 2 is 100 X more acidic than a p. H of 4. n n p. H paper can be used to determine the p. H of liquids. n Changes colours depending on the p. H of the substance it’s in.
Homework Read pages 268 -273 n Answer Check Your Learning questions 2, 3, 5 and 8 on Page 271 n
- Slides: 8