16/10/2015 Acids and Bases Hydrochloric acidCitric acidWater An acid is a “proton donor”: A base is a “proton acceptor”: H Cl H +- H O Na H O - + Sodium hydroxideAmmonia

16/10/2015 Common acids and alkalis AcidsAlkalis Hydrochloric acid, HClSodium hydroxide, NaOH Nitric acid, HNO 3 Sulphuric acid, H 2 SO 4 Potassium hydroxide, KOH Magnesium hydroxide, Mg(OH) 2 Calcium hydroxide, Ca(OH) 2

16/10/2015 Arrhenius vs Lowry and Bronsted Arrhenius, Lowry, I said that all acids release hydrogen ions and all alkalis form hydroxide ions when dissolved in water. Bronsted and I said that acids are “proton donors” and bases are “proton acceptors”. Bronsted and Lowry’s work was more accepted because of three things: 1)Arrhenius’ work depended on the existence of subatomic particles like protons, which hadn’t yet been discovered. 2)Arrhenius’ work couldn’t explain the behaviour of acids and bases in solvents other than water 3)Lowry and Bronsted worked independently but still agreed with each other

HNO 3 - nitric acid HCl- hydrochloric acid H 2 SO 4 - sulphuric acid Acids donate protons Acids and Bases Sulphuric acid can donate two proton and so we say it is diprotic HNO 3(aq)  H + (aq) + NO 3 - (aq)

Metal oxides and metal hydroxides. Ammonia and organic compounds called Amines (e.g. CH 3 NH 2 ) are also bases Acids and Bases Bases accept protons MgO – magnesium oxide NaOH- sodium hydroxide NH 3 - ammonia

Alkalis are soluble bases that release hydroxide ions into water LiOH - lithium hydroxide Mg(OH) 2 - magnesium hydroxide Alkalis

7 Biological Acid & Bases These include - Fatty acids Amino acids Nucleic acids

8 Amino Acids Building blocks of proteins Carboxylic acid group Amino group Side group R gives unique characteristics R = side chain H H 2 N—C—COOH R Acid Base These molecules have both acid and base properties. We say they are amphoteric.

A small amount of solid magnesium oxide, MgO, was reacted with excess dilute hydrochloric acid. (a)Write a balanced equation for this reaction [1] (b) Describe what would be seen as the reaction occurs solid disappears/dissolves/colourless solution forms MgO (s) + 2HCl (aq)  MgCl 2(aq) + H 2 O (l) [1]

16/10/2015