molkg

Molkg is commonly used to refer to the unit of molality, expressed as mol per kilogram (mol/kg). In chemistry, molality (symbol m) defines the amount of solute in moles per kilogram of solvent. This concentration measure is preferred in many physical chemistry contexts because, unlike molarity, it is largely independent of temperature and solution volume.

Molality is calculated by dividing the amount of solute (in moles) by the mass of the solvent (in kilograms). The formula is m = n_solute / m_solvent(kg). When solving problems, the mass used is the mass of the solvent, not the total solution mass, and the solute’s mass is not included in the denominator. For example, dissolving 2.0 moles of solute in 0.500 kg of solvent yields a molality of 4.0 mol/kg.

Molality is especially important in the study of colligative properties, such as freezing point depression and boiling point elevation, where changes depend on the number of dissolved particles and on molality, not on solution volume. The effect is often expressed as ΔT = i Kb m, where i is the van’t Hoff factor and Kb is the solvent’s ebullioscopic constant. Thus, molality provides a more intrinsic measure of concentration when temperature or density changes occur.

The conventional notation uses either mol/kg or the symbol m for molality. While molarity (mol/L) is more common in many laboratory contexts, molality remains a key concept for understanding how solute particles affect solvent properties under varying conditions.