U2 S1 L4 Writing Bronsted-Lowry equations: predictions. P 562

Upon completion of this lesson, you should be able to: predict the most likely acid-base reaction using a table of relative acid-base strengths predict whether or not an acid-base reaction goes to completion and use appropriate symbols to represent equilibrium and non-equilibrium acid-base systems predict whether reactants or products are favoured in an acid-base equilibrium write total ionic and net ionic equations specific to acid- base reactions

Net ionic review: net ionic equations –display only the species that actually undergo some change in bonding. (recall that spectator ions cross out) Ex: silver nitrate reacts with potassium chloride 1.Total non-ionic equation: 2.Total ionic equation: 3.Net ionic equation:

Steps for writing Net ionic equations for Bronsted Lowry Acid/Base reactions 1.List all species present. Ionic compounds 100% dissociated Strong acids (100% ionized) Weak acid (written in full) Water is always present 2.Identify strongest acids/bases (use table) 3.Write the acid / base reaction using the stronger acid and stronger base. 4.Determine the nature of the reaction: –Stoichiometric (100% single arrow) reactions occur between: hydronium and bases stronger than nitrite in the acid-base table. hydroxide and acids stronger than hypochlorous acid in the acid-base table. –Non-stoichiometric (< 100% double arrow) reactions occur between: weak acids and weak bases. hydronium and bases weaker than fluoride. hydroxide and acids weaker than hydrogen sulfite.

5. Determine the position of equilibrium. Consider the acid / conjugate acids strengths –if the acid is stronger than the conjugate acid, the equilibrium lies to the right: products are favoured –if the conjugate acid is stronger than the acid, then the equilibrium lies to the left: reactants are favoured

1) Write an equation for the acid-base reaction between aqueous sodium hydroxide and hydrochloric acid.

2) Write an equation for the acid-base reaction between nitrous acid and aqueous sodium sulfite

3) Write an equation for the acid-base reaction between hydrochloric acid and aqueous sodium sulfide The horizontal line between nitrite and fluoride in the acid-base strength table is used to determine whether or not this reaction is stoichiometric. In this case S 2- is a stronger base than nitride, thus stoichiometric.

4) A paste of baking soda can be used to neutralize a sodium hydroxide spill. Write an equation for the acid-base reaction between aqueous sodium hydroxide and aqueous sodium hydrogen carbonate The horizontal line between hydrogen sulfite and hypochlorous acid in the acid-base strength table is used to determine whether or not this reaction is stoichiometric. hydrogen carbonate well below the short horizontal line, thus non- stoichiometric.

5) Oven cleaner (aqueous NaOH) is neutralized by vinegar (CH 3 COOH). Write the equation for the Brønsted-Lowry acid-base reaction that should take place.

Extra Practice: Write equations for acid-base reactions for each pair of given substances. You can assume that ionic compounds are aqueous. 1.sodium sulfate and ammonium 2.sodium carbonate and acetic acid 3.ammonia and nitrous acid 4.nitric acid and rubidium hydroxide 5.sulfurous acid and potassium phosphate 6.benzoic acid and sodium hydroxide 7.oxalic acid and potassium hydrogen phosphate 8.hydrofluoric acid and ammonium acetate 9.carbon dioxide dissolved in water and potassium sulfide 10.aqueous sulfur dioxide and aqueous ammonia 11.sodium bicarbonate and gastric acid (HCl) 12.potassium hydrogen sulfate and sodium carbonate