Question

A 10g Licl with initial temperature of 20 degrees and delta H is -34.4kJ/mol, was added to 100g of water with a temperature of of 20 degrees. after Licl is added to water, the mixture has a final temperature of 37.63 degrees. what mass of licl is needed to change the temperature of 100g water from 20 degrees to 40 degrees? report the answer in grams.

Answer 1

10g of Licl to added to 100g of water at 20°c. Temperature of the water increased from 20 c to 37.63°C. For this reaction th=-34.4 kJ/mol Now molar mass of Lic=42.394 g/mol 10 g 42.3948/mol ni 10g of Licla 0.2359 mol(n) AT = Tf - Ti = (37.63°C -200°C) -17.63°C Therefore 0.2359 mol of Licl increased the temperature of loog of water by 17163°C. Now we need to find the mass Lidl which can increase the temperature of 100g of water from 20° to 40°C. AT2= the If- Ti = 40%-20% = 20°C In both the cases mass of water is same that is 100 g : Suppose number of motes of Licl required for this process -12 AT2 Х ATI 20°C x 0.2359 mo 17,63°C 0.2676 mol Now 0.2676 mol Lich = 0.2676 mot X 42.394 g/mol 11.3446 g Therefore mass of Licl needed to change the temperature of water from 20% to hoc is 11:3446g .. N2=