The molal boiling-point elevation constant (Kb) for water is 0.512 °C/m.
This value represents the increase in boiling point observed when 1 mole of a nonvolatile solute is dissolved in 1 kilogram of water. Kb is a crucial constant used in colligative properties calculations, specifically when determining the boiling point elevation of solutions.
Here's a breakdown of what Kb signifies:
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Kb Definition: Kb (also called the ebullioscopic constant) is the molal boiling point elevation constant. It's a characteristic of the solvent (in this case, water).
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Units: The units for Kb are typically expressed as °C/m or K/m, where "m" represents molality (moles of solute per kilogram of solvent).
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Application: Kb is used in the following formula to calculate the boiling point elevation (ΔTb):
ΔTb = Kb m i
Where:
- ΔTb is the change in boiling point
- Kb is the molal boiling point elevation constant
- m is the molality of the solution
- i is the van't Hoff factor (number of particles the solute dissociates into)
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Importance: Knowing the Kb value allows scientists and chemists to predict and calculate the boiling points of solutions containing various solutes. This is essential in many laboratory and industrial processes.
