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Preparation of standard solutions.

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Introduction

Topic: Preparation of standard solutions. PLANNING (A) A solution is a homogeneous mixture of two or more substances, which may be solids, liquids, gases, or a combination of these. A titration is a method of analysis that will allow you to determine the precise endpoint of a reaction and therefore the precise quantity of reactant in the titration flask. A burette is used to deliver the second reactant to the flask and an indicator or pH Meter is used to detect the endpoint of the reaction. Hypothesis: If the mass of potassium hydrophtalane and the volume of NaOH used in each trial are known, we may find out an exact concentration of NaOH solution. Key variables: mx - weighted amount of KHC8H4O4 in each trial Vx - volume of NaOH solution in each trial CNaOH - exact concentration of NaOH solution in each trial PLANNING (B) ...read more.

Middle

4. The above procedure was repeated 3 times to obtain 3 results. DATA COLLECTION HCl + NaOH � NaCl + H20 mNaOH = 5 g Vsolution = 1 dm3 CNaOH = 0.1 mol dm-3 V1 = 32.2 cm3 V2 = 36.8 cm3 V3 = 21.5 cm3 m1 = 0.791 g m2 = 0.903 g m3 = 0.528 g Mpotassium hydrophtalane = 204.22 g mol-1 CNaOH = mx / Vx Mpotassium hydrophtalane mx - weighted amount of KHC8H4O4 in each trial Vx - volume of NaOH solution in each trial Mpotassium hydrophtalane - molar mass = 204.22 g mol-1 In the equations below molar mass of potassium hydrophtalane is shortened to Mph DATA PROCESSING & PRESENTATION C1 = m1 / V1 Mph = 0.791g / 32.2 cm3 * 204.22 mol = 0.12028 g mol dm-3 C2 = m2 / ...read more.

Conclusion

worked well. The experiment was rather a simple one. The purpose of it was to make us understand and apply titration in practice and not only theory. Although observing the exact moment of changing the colour of the solution from orange to yellow may be difficult and misleading, the results confirm that the substances were measured accurately. Errors made in this experiment should not have exceeded 1% of total mass of the substances. As far as classroom conditions are concerned it is a good result. This lab was not very complicated and there were not any possibilities to have the results upset i.e. by emitting gas or heat. It would be better, however, if the burettes worked from the very beginning and were airtight. SOURCES: 1. Green J, Damji S. 2001. Chemistry. Second edition. IBID Press, Victioria, Australia. 2. http://www.answers.com/topic/solution 3. http://www.dartmouth.edu/~chemlab/techniques/titration.html PREPARATION OF STANDARD SOLUTIONS 1 ...read more.

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