Determination of an Enthalpy change of a Reaction

# Determination of an Enthalpy change of a Reaction - (II)...

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Introduction The reaction between zinc and copper (II) sulphate is endothermic. If an excess of zinc powder is added to a measured amount of aqueous copper (II) sulphate in a calorimeter and the temperature change is recorded over a period of time, the enthalpy change of the reaction can be experimentally determined. Assumption 1. Mass of H 2 O in 100cm 3 of CuSO 4 solution is 100g 2. Specific heat of solution is 4.18 kJ kg -1 K -1 which is the same as the specific heat of water 3. Heat evolved in the reaction will be absorbed by the CuSO 4 solution 4. Maximum temperature that would have been reacted if no heat lost to surroundings can be calculated by extrapolation the graph plotted with temperature against time. Procedure I. Measure 100cm3 of the copper sulphate solution into the II. Weigh about 5 grams of zinc powder. III. Place the thermometer through the hole in the calorimeter lid then put the thermometer into the copper

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Unformatted text preview: (II) sulphate solution. Try to keep the solution covered as much as possible from this point on. IV. Record the temperature of the copper (II) sulphate solution to the nearest 0.1 o C every 60.0 seconds for 25 minutes. V. At precisely 3.0 minutes, add zinc powder to the cup. Swirl the mixture gently. VI. Continue to swirl the contents of the calorimeter and record the temperature for an additional 6 minutes. VII. Dispose of the products of this reaction in the waste container. Zn (s) + CuSO 4(aq) Cu (s) + ZnSO 4(aq) Amount of CuSO4 = Amount of Zn = Therefore Zn is the limiting reagent Mass of H2O = Heat evolved = Therefore enthalpy change for the reaction Uncertainty in H = % of uncertainty in mass of Zn + % of uncertainty in time + % o f uncertainty in temperature + % of uncertainty in time...
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## This note was uploaded on 12/12/2011 for the course COMP 0112 taught by Professor Mr.kwok during the Summer '11 term at Hong Kong Baptist University, China.

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Determination of an Enthalpy change of a Reaction - (II)...

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