The standard enthalpy of formation of RbF(s)is -557.7kJ/mol and the standard enthalpy of formation of RbF(aq,1 m)is -583.8 kJ/mol.Determine the enthalpy of solution of RbF and indicate whether the solution temperature will increase or decrease when RbF is dissolved in water.
A) -26.1 kJ/mol; increase
B) 26.1 kJ/mol; increase
C) -26.1 kJ/mol; decrease
D) +1141.5 kJ/mol; increase
E) -1141.5 kJ/mol; decrease

Question

Quizplus · Accepted Answer

The enthalpy of solution can be calculated as follows:
ΔHsolution = ΔHf(aq) - ΔHf(s)
ΔHsolution = (-583.8 kJ/mol) - (-557.7 kJ/mol)
ΔHsolution = -26.1 kJ/mol

The negative sign indicates that the process is exothermic, meaning that energy is released when RbF dissolves in water. This energy will be transferred to the solution, causing an increase in temperature, so the solution temperature will increase. Therefore, the correct answer is choice A.

The Standard Enthalpy of Formation of RbF(s)is -557