1. Acids and Bases and Salts Revision IGCSE 620

2. Which ions are definitely given out from an acid? and alkali? when mixed with water Acid H+ ions (hydrogen ion/proton) Alkali OH- ions (hydroxide ions) Name the gas produced when a metal reacts with acid Hydrogen H2 Name the gas when a metal reacts with a metal carbonate. Carbon dioxide CO2 Excess Copper(II) oxide were added to sulphuric acid. Predict the pH of the solution before and at the end of the reaction Before: 1(strong acidic) after: 9 (alkaline) How will you remove the excess of Copper(II) oxide? By filtration

3. Write an equation to show the reaction of Hydrochloric acid with sodium carbonate. HCl(aq) + Na2CO3(s)  NaCl(aq) + CO2(g) + H2O(l) Give examples of: Acidic oxide: CO2; SO2; NO2 Basic oxide: CuO; MgO; CaO Neutral oxide: H2O; CO; N2O Amphoteric oxide: Al2O3; ZnO; PbO2 CaO(s) + 2HNO3(aq)  Ca(NO3)2(aq) + H2O(l) What kind of reaction is this? Neutralisation What is the meaning of rate of reaction ? Speed at which a reaction takes place

4. State any three factors which can make the rate of reaction high. High concentration of reactants High temperature Use of a catalyst Powdered chemicals What are alloys? Explain why alloys are more useful than many metals. Alloys are mixtures of metals with other elements Alloys are stronger and durable. What will you see if excess zinc powder is added to copper(II) sulphate solution? Blue colour slowly disappears and pink copper metal appears What kind of reaction is this? Displacement Write an equation for the reaction. Zn(s) + CuSO4(aq)  Cu(s) + ZnSO4(aq) How will you remove excess of zinc from the mixture? By filtration

5. Why indicators are used in titration? A colour change shows the end point of the reaction Why Universal indicator is better than other indicators? Gives different colours at different pH Which common reactions will produce salt? Metal + acid  salt + Hydrogen Metal oxide + acid  Salt + water Metal hydroxide + acid  salt + water Metal carbonate + acid  salt + carbon dioxide + water Soluble salt solution + soluble salt solution  insoluble salt An ammonium NH4+ salt is heated with an alkali. Which gas is produced? Ammonia gas How ill you test this gas? Turns litmus colour to blue What can be the use of this test? Test for the presence of ammonium ion in a salt NH+ What is the difference between a strong acid and a weak acid? Give two examples of each. Strong acid ionises completely while weak acid ionises partially.