themo chemistry

Question

 What is the change in temperature when 3.00 grams of calcium chloride is dissolved in 100 mL of water?  5.19^oC

Given the change in the temperature from adding 3.00 grams of calcium chloride to 100.00 mL of water, calculate the enthalpy of solution for calcium chloride in units of kJ/mol.  kJ/mol

 

Answer 1

I'm assuming the change in temperature is 5.19ºC.

q = heat = mC∆T

q = (3.00 g)(4.184 J/g/ºC)(5.19ºC)

q = 65.1 J and this is the heat for 3.00 g. To get J/mole or kJ/mole, we will convert 3.00 g CaCl2 to moles.

3.00 g CaCl2 x 1 mol/111 g = 0.0270 moles

Enthalpy of solution = 65.1 J/0.027 0 mole = 2411 J/mole = 2.41 kJ/mole