Question

Certainly! Here's a precise problem for the student to solve:Calculate the standard enthalpy change ($\Delta H^\circ$) for the dissolution reaction of 5.00 g of lithium chloride ($\text{LiCl}$) in 150.0 mL of water, given that the density of water is 1.00 g/mL and the final temperature of the solution is 25.0$^\circ$C. The molar enthalpy of solution of $\text{LiCl}$ is -3.00 kJ/mol.

Answer 1

To calculate the standard enthalpy change for the dissolution of lithium chloride, we first need to determine the number of moles of LiCl dissolved and then use the molar enthalpy of solution to find the total enthalpy change.1. Calculate the number of moles of LiCl:The molar mass of LiCl is approximately 6.94 g/mol  Li  + 35.45 g/mol  Cl  = 42.39 g/mol.So, the number of moles of LiCl is: 5.00 g LiCl  /  42.39 g/mol  = 0.118 mol LiCl2. Calculate the standard enthalpy change:Now that we have the number of moles of LiCl, we can use the molar enthalpy of solution to find the total enthalpy change:H =  0.118 mol LiCl    -3.00 kJ/mol  = -0.354 kJThe standard enthalpy change for the dissolution of 5.00 g of lithium chloride in 150.0 mL of water is -0.354 kJ.