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Calculate The Boiling Point of Ethanol in Degrees Celsius

Reviewed by Calculator Editorial Team

Ethanol (C₂H₅OH) is a common organic compound with a boiling point that varies based on atmospheric pressure and purity. This guide explains how to calculate the boiling point of ethanol in degrees Celsius using standard conditions and provides practical applications of this calculation.

Introduction

The boiling point of ethanol is an important property in chemistry, biology, and industrial applications. Ethanol's boiling point at standard atmospheric pressure (1 atmosphere) is approximately 78.37°C (173.07°F). However, this value can vary slightly depending on the purity of the ethanol and the exact atmospheric pressure.

Understanding how to calculate the boiling point of ethanol helps in various scientific and industrial processes, including distillation, solvent selection, and chemical reaction optimization.

Boiling Point Formula

The boiling point of ethanol can be calculated using the following formula:

Boiling Point (°C) = 78.37 + (0.000015 × (Pressure - 101.325))

Where:

  • 78.37°C is the standard boiling point of pure ethanol at 1 atmosphere (101.325 kPa).
  • Pressure is the atmospheric pressure in kilopascals (kPa).
  • 0.000015 is the coefficient that accounts for the change in boiling point with pressure.

This formula provides a good approximation for the boiling point of ethanol under different pressure conditions.

Factors Affecting the Boiling Point of Ethanol

The boiling point of ethanol is influenced by several factors:

  1. Atmospheric Pressure: Higher pressure increases the boiling point, while lower pressure decreases it.
  2. Purity: Impurities in ethanol can lower its boiling point.
  3. Concentration: Diluting ethanol with water lowers its boiling point.
  4. Temperature: The boiling point is also affected by the surrounding temperature.

Note

The formula provided assumes pure ethanol and standard temperature conditions. For more precise calculations, consult specialized literature or use advanced thermodynamic models.

Worked Example

Let's calculate the boiling point of ethanol at a pressure of 95 kPa:

Boiling Point (°C) = 78.37 + (0.000015 × (95 - 101.325)) Boiling Point (°C) = 78.37 + (0.000015 × (-6.325)) Boiling Point (°C) = 78.37 - 0.000094875 Boiling Point (°C) ≈ 78.36°C

At 95 kPa, the boiling point of ethanol is approximately 78.36°C, which is slightly lower than the standard boiling point due to the reduced pressure.

FAQ

What is the standard boiling point of ethanol?

The standard boiling point of pure ethanol at 1 atmosphere (101.325 kPa) is 78.37°C.

How does pressure affect the boiling point of ethanol?

Increased pressure raises the boiling point, while decreased pressure lowers it. The formula accounts for this relationship.

Why does impure ethanol have a lower boiling point?

Impurities disrupt the hydrogen bonding in ethanol, reducing the energy required to break these bonds and lower the boiling point.

Can I use this formula for other alcohols?

No, this formula is specific to ethanol. Different alcohols have different boiling points and require their own formulas.