In this question you will use your data from Table 8-1 provided below to determi

Question

In this question you will use your data from Table 8-1 provided below to determine DeltaHfusion for water for Part 1, Procedure 1 of the lab. Let's go through the calculations. Determine the temperature change of the melted ice in each trial. Please review your entries and make corrections where necessary. Determine the absolute value of the heat "lost" by the water originally in the calorimeter in each trial. Determine the absolute value of the heat "gained" by the melted ice in each trial. Do not consider the heat involved in melting the ice (that is for Part 7). Determine DeltaHfusion for water for each trial in units for kj/mol. Determine the average value DeltaHfusion for water in units for kj/mol. The acceptable value for DeltaHfusion for water is 6.0 kj/mol. Determine the percent error (absolute value) for your average value of DeltaHfusion for water.

Explanation / Answer

#Trail 1

Change in temperature of ice = 28.5 C

Heat lost by water = (60.5-28.5)*4.2*70 = 9408 J

Heat gained by melted ice = (28.5-0)*4.2*(127.14-99.58) = 3298.932 J

No of moles of ice = (127.14-99.58)/18 = 1.53

Heat spent on melting of ice = 9408-3298.932 = 6109 J

H fusion = 6.109/1.53 = 4 kJ/mol

#Trial 2

Change in temperature of ice = 25.5 C

Heat lost by water = (60.0-25.5)*4.2*70 = 10143 J

Heat gained by melted ice = (25.5-0)*4.2*(124.82-99.58) = 2703.204 J

No of moles of ice = (124.82-99.58)/18 = 1.4

Heat spent on melting of ice = 10143-2703.204 = 7439.8 J

H fusion = 7.439/1.4 = 5.31 kJ/mol

Average value = (4+5.31)/2 = 4.655 kJ/mol

%age error = (6-4.655)/6*100 = 22.41%

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