Doc Brown's Chemistry GCE AS A2 Level Chemistry Advanced Level Chemistry Revision on Titrations GCE A Level ASA2 IB Acidbase and other nonredox volumetric titration quantitative calculation questions PART 2 Questions 21 onwards In PART 2 of these A Level quantitative chemistry calculation questions you have to work out the method a bit more on your own! I have not broken the problems down into 'ministeps' for you, but request you use your experience from solving the PART 1 Questions. I have also included some 'gas volume' and 'gravimetric analysis' questions to provide more variation of quantitative analysis questions and standardising hydrochloric acid calculations. PART 1 Questions * PART 1 Question Answers PART 2 Question Answers * Redox Titration Q's * Qualitative Analysis If you find these useful or spot a silly error please EMAIL query?comment ILLUSTRATIONS OF ACIDALKALI TITRATIONS and SIMPLE STARTER CALCULATIONS I DO MY BEST TO CHECK MY CALCULATIONS, as you yourself should do, BUT I AM HUMAN! AND IF YOU THINK THERE IS A 'TYPO' or CALCULATION ERROR PLEASE EMAIL ME ASAP TO SORT IT OUT!
Relative atomic masses that may be needed: H = 1, C = 12, O = 16, Na = 23, S = 32, Cl = 35.5, Ca = 40, Cu = 63.5, for questions 21 onwards I've tried to quote the data to the appropriate significant figures and associated 'trailing zeros'. Q21 Analysis of limewater. 25.0 cm^{3} aliquots of a calcium hydroxide solution were titrated with 0.100 mol dm^{3} (0.100M) hydrochloric acid using phenolphthalein indicator. On average it took 10.50 cm^{3} of the acid to neutralise the limewater.
Q22 If it took 20.55 cm^{3} of 0.100 M HCl to neutralise 25.0 cm^{3} of an NaOH solution, calculate the molarity of the alkali.
Q23 A standardised solution of sodium hydroxide had a concentration of 0.1025 mol dm^{3} (0.1025M). If 25.0 cm^{3} of a sulfuric acid solution required 17.65 cm^{3} of the NaOH to neutralise it, calculate the molarity of the acid.
Q24 Citric acid has the formula and is tribasic acid, forming the trisodium salt on complete neutralisation with sodium hydroxide.
Q25 4.28 g of a hydrated form of the salt sodium sulphate, Na_{2}SO_{4}.xH_{2}O, was heated at 180^{o}C until the remaining mass became constant at 1.89 g. Calculate x, the number of molecules of 'water of crystallisation'.
Q26 On reaction with dilute hydrochloric acid, 0.428 g of a group 2 metal (M) formed 75.0 cm^{3} of hydrogen gas at 298K/1 atm pressure.
Q27 To standardise a solution of hydrochloric acid, it was titrated against accurate masses of anhydrous sodium carbonate (which should be dried in an oven prior to use). e.g. 0.132 g of Na_{2}CO_{3} required 24.8 cm^{3} of the hydrochloric acid for complete neutralisation, calculate the molarity of the hydrochloric acid.
Q28 Follows on from Q27. You can make up a solution of sodium carbonate from which you pipette 25.0 cm^{3} aliquots to obtain an accurate average titration value as an alternative to multiple weighings. 1.30g of anhydrous sodium carbonate was dissolved in 250 cm^{3} of deionised water in a volumetric flask. 25.0 cm^{3} aliquots were pipetted and titrated with a hydrochloric acid solution (in the burette) to be standardised.
Q29 The purity of anhydrous sodium carbonate can be determined by titration with standard hydrochloric solution. The following results were obtained on titrating accurately weighed amounts of sodium carbonate with 1.00 mol dm^{3} hydrochloric acid (1.00 M HCl) to complete neutralisation given by the equation below.
Q30 How to determine the water of crystallisation in hydrated sodium carbonate crystals ('washing soda') by titration with standard hydrochloric acid solution.
Q31 Blue hydrated copper(II) sulfate crystals have the formula CuSO_{4}.xH_{2}O, where x is the number of molecules of 'water of crystallization'.
Q32 It is possible to analyse a mixture of sodium hydrogencarbonate and anhydrous sodium carbonate, either as a solid or solution, by titration with a standard acid solution e.g. 0.1 to 1.0 mol/dm^{3 }hydrochloric acid.
Q33 Sodium hydroxide solution can be used to absorb carbon dioxide gas. 2 dm^{3} (2 litres) of a sodium hydroxide solution was used to cleanse a gas mixture of carbon dioxide. The resulting solution X now consists of a mixture of unreacted sodium hydroxide and sodium carbonate. Solution X was titrated with standard 1.000 mol/dm^{3} hydrochloric acid ...
PART 1 Questions * PART 1 Question Answers * PART 2 Question Answers * Redox Titration Q's I DO MY BEST TO CHECK MY CALCULATIONS, as you yourself should do, BUT I AM HUMAN! AND IF YOU THINK THERE IS A 'TYPO' or CALCULATION ERROR PLEASE EMAIL ME ASAP TO SORT IT OUT! ILLUSTRATIONS OF ACIDALKALI TITRATIONS and SIMPLE STARTER CALCULATIONS Advanced Level ORGANIC CHEMISTRY REVISION STUDY NOTES Advanced Level INORGANIC CHEMISTRY REVISION STUDY NOTES Advanced Level PHYSICALTHEORETICAL REVISION STUDY NOTES

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