Final answer:
The molar heat of the solution of RbBr is -22.099 kJ/mol
Step-by-step explanation:
The molar heat of the solution of RbBr can be calculated using the formula:
q = mcΔT
Where q is the heat absorbed or released by the system, m is the mass of the solution (7g in this case), c is the specific heat capacity of the solution (equal to the heat capacity of the water in this case), and ΔT is the change in temperature (-0.390 K in this case).
Using the given total heat capacity of the calorimeter (2.38 kJ times K-1) and the change in temperature, we can calculate the heat absorbed or released:
q = (2.38 kJ/K) * (-0.390 K)
q = -0.9282 kJ
Since the heat absorbed or released is per K, to calculate the molar heat, we divide by the number of moles in the sample. The molar mass of RbBr is 165.364 g/mol.
moles = mass / molar mass = 7g / 165.364 g/mol = 0.042 moles
Molar heat of the solution = q / moles = -0.9282 kJ / 0.042 moles = -22.099 kJ/mol