CH105 Chemistry of Applied Science

The following problems are samples of the kinds of kinetics questions that you are likely to meet in short tests and examinations. We strongly encourage you to attempt the problems and check your answer with your tutor in the tutorial class.1.A sample of 0.6760g of an unknown compound containing barium ions (Ba2+) is dissolved in water and treated with excess of Na2SO4. Barium Sulphate (BaSO4) precipitates are formed. i.Write the balanced chemical equation for this reaction.ii.If the mass of BaSO4precipitate formed is 0.4105g, what is the percent by mass of Ba2+in the original unknown compound?2.Molality (m) is used for expressing concentration. i.What is the unit for molality?ii.25g of magnesium chloride (MgCl2) was dissolved in250ml distilled water at 25oC. The densityof waterwas 0.9975g/cm3. Calculate the concentration in molality.3.A 0.4671 g sample containing sodium bicarbonate was dissolved and titrated with a solution of hydrochloric acid, requiring 40.72 ml. The reaction isHCO3-+ H+?H2O + CO2The hydrochloric acid was standardised by titrating 0.1876 g sodium carbonate by the following reaction:CO32-+2H+?H2O + CO2The titration required 37.86 cm3acid. Calculate the percent sodium bicarbonate in the sample.4.What is a buffer solution and what is so significant about this solution?5.Define the following terms:i.autoprotolysisii.Molarity, Molality and parts per million.iii.pH and pOHiv.mole.6.A 46.2ml , 0.568M calcium nitrate [Ca(NO3)2] solution is mixed with 80.5ml of 1.396M calcium nitrate solution. Calculate the concentration of the final solution