Am I Correct in assuming this?

dH of solution = -dH of lattice enthalpy + dH of hydration

E.g:
dHsolution NaCl = -dHLE NaCl(s) + dHhyd Na+(g) + dHhyd Cl-(g)

Units as kJmol-1

Your signs on the right side are reversed. Bond breaking is endothermic and bond formation is exothermic. Some bond formations are endothermic (i.e. hydrogen bonding) that must be taken into account in conjunction with hydration which is also bond formation.

∆H(soln) = |∆H(lattice)| - ∆H(solute-solvent)

How is this Possible GK.

Everywhere I have looked, including mark schemes and chemistry websites dH(solution) is worked out via this equation:

dH(solution) = dH(LE) - dH(hyd) + dH(hyd)

What is it you are working out with solute and solvent?

Yes, your assumption is correct.

The enthalpy change of a solution can be calculated by considering the individual enthalpy changes involved in the process. In this case, the enthalpy change of the solution (dHsolution) of NaCl can be determined by summing the enthalpy change of lattice enthalpy (dHLE) and the enthalpy changes of hydration of Na+ and Cl- ions (dHhyd Na+ and dHhyd Cl-).

The enthalpy change of lattice enthalpy (dHLE) represents the energy required to break apart the solid NaCl lattice into its constituent ions in the gaseous state. It has a negative sign because energy input is needed to overcome the attractive forces between the ions.

The enthalpy changes of hydration (dHhyd) represent the energy released when individual Na+ and Cl- ions in the gaseous state are surrounded by solvent molecules (typically water) and form hydrated ions. These enthalpy changes are typically negative since the solvation process is exothermic (releases energy).

Therefore, according to your assumption:

dHsolution NaCl = -dHLE NaCl(s) + dHhyd Na+(g) + dHhyd Cl-(g)

The units for these enthalpy changes are typically given in kJmol-1, which means the energy change per mole of the substance.

By calculating these individual enthalpy changes and substituting their values into the equation, you can determine the overall enthalpy change of the solution.