K2co3 Lab Report

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THE CALCULATION OF THE ENTHALPY CHANGE FOR DECOMPOSITION OF KHCO3 This question is given to you to develop and practice some planning and analytical skills before an assessed practical. KHCO3, like NaCO3 in baking powder, decomposes to give the metal carbonate + carbon dioxide. The equation for the reaction is: 2KHCO3(s) → K2CO3(s) + CO2 (g) + H2O(l) It is impossible to measure this directly, but a Hess Law cycle can be established which allows its practical measurement. It involves adding hydrochloric acid to both reactants and products. Some data for the experiments is given below: 1. Reaction of KHCO3 with 30cm3 of 2M HCl Mass of KHCO3 used = 3.42g Temperature drop = 7.35oC 2. Reaction of K2CO3(s)…show more content…
Your report should include: 1. An outline (of not more than 100 words) of how you would tackle the problem. 2. Requirements to accomplish the task. (A list of apparatus and materials needed including the quantities of substances needed and the reasons for choosing these quantities.) 3. The experimental method, including full experimental details and the necessary safety precautions. 4. Result tables for recording numerical data to be collected during the experiment. 5. Treatment of results, including how you will use your results to calculate the enthalpy change, the assumptions made and the possible sources of error. Proposed mark scheme: The mark scheme can cover the following areas: (1) Appropriate outline of the method (2) List of apparatus/materials required Quantities of materials used (calculations showing how the quantities are worked out.) Use of excess…show more content…
2NaHCO3(s) ï‚® Na2CO3(s) + H2O(l) + CO2(g) This enthalpy change is difficult to measure directly. By determining the enthalpy changes for the reactions between sodium carbonate and hydrochloric acid, and sodium hydrogencarbonate and hydrochloric acid, it is possible to determine, indirectly, the enthalpy change for the decomposition of sodium hydrogencarbonate. In this experiment you are required to measure the enthalpy change for the sodium carbonate reaction. Procedure 1. Set up a burette to transfer 30.00 cm3 of approximately 2M hydrochloric acid into a clean dry plastic cup. Note the final burette reading. 2. Place the plastic cup in a beaker to provide insulation, and mount the thermometer and stirrer in the cup using a clamp and stand. The bulb of the thermometer must be fully immersed in the liquid. 3. Weigh out accurately between 2.50 and 3.00 g of anhydrous sodium carbonate. Record your mass. 4. Record the temperature of the acid in the cup. Construct a suitable table for your
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