Boiling Point Elevation Calculator
What This Calculator Does
The Boiling Point Elevation Calculator determines how much a solvent's boiling point increases when a non-volatile solute is dissolved in it. This is one of the four colligative properties of solutions, meaning it depends only on the concentration of solute particles, not their identity.
When you add salt to water, sugar to water, or any non-volatile solute to a solvent, the boiling point rises. This calculator uses the formula ΔTb = Kb × m × i to calculate this elevation, where:
- ΔTb - Boiling point elevation (temperature increase in °C or K)
- Kb - Ebullioscopic constant (specific to each solvent)
- m - Molality of the solution (mol solute/kg solvent)
- i - Van't Hoff factor (number of particles per formula unit)
Formula & Calculation Method
Core Formula
Where:
- ΔTb = Boiling point elevation (°C)
- Kb = Ebullioscopic constant (°C·kg/mol)
- m = Molality (mol/kg)
- i = Van't Hoff factor (dimensionless)
Common Kb Values:
Water: 0.512 °C·kg/mol
Benzene: 2.53 °C·kg/mol
Ethanol: 1.22 °C·kg/mol
Chloroform: 3.63 °C·kg/mol
Van't Hoff Factor (i):
Non-electrolytes (sugar, urea): i = 1
NaCl: i ≈ 2 (Na⁺ + Cl⁻)
CaCl₂: i ≈ 3 (Ca²⁺ + 2Cl⁻)
Al₂(SO₄)₃: i ≈ 5 (2Al³⁺ + 3SO₄²⁻)
Step-by-Step Example
Problem: What is the boiling point of a solution made by dissolving 58.5 g of NaCl in 1.00 kg of water?
Step 1: Calculate molality
Molar mass of NaCl = 58.5 g/mol
Moles = 58.5 g ÷ 58.5 g/mol = 1.00 mol
m = 1.00 mol ÷ 1.00 kg = 1.00 m
Step 2: Identify constants
Kb (water) = 0.512 °C·kg/mol
i (NaCl) = 2 (dissociates into Na⁺ and Cl⁻)
Step 3: Calculate ΔTb
ΔTb = 0.512 × 1.00 × 2 = 1.024 °C
Step 4: Find new boiling point
Normal BP of water = 100.0 °C
New BP = 100.0 + 1.024 = 101.024 °C
Real-World Applications
🍳 Cooking
Adding salt to water increases boiling point, cooking pasta slightly faster. At high altitudes, lower atmospheric pressure decreases boiling point.
🚗 Automotive
Antifreeze solutions raise the boiling point of engine coolant, preventing overheating in summer while lowering freezing point in winter.
🔬 Laboratory
Determine molecular mass of unknown substances by measuring boiling point elevation. Used in physical chemistry experiments.
🏭 Industry
Process control in chemical manufacturing. Desalination plants use boiling point differences for water purification.
Quick Reference
Units
°C, mol/kg
Formula
ΔTb = Kb × m × i
Applications
Cooking, automotive
Level
College chemistry
Related Calculators
Freezing Point Depression
Calculate ΔTf
Molality Calculator
Calculate molal concentration
Ideal Gas Law
PV = nRT calculations
Related Formulas
Where It's Used
Culinary
Salt water cooking
Automotive
Engine coolant
Research
Molecular mass determination
Industry
Process control