Enthalpy of Water Calculator

The Enthalpy of Water Calculator measures the total energy change in water due to temperature variation and/or phase changes (like melting or vaporization). This is a vital tool in thermodynamics, chemical engineering, HVAC systems, and environmental science. It helps users determine how much heat is absorbed or released when water is heated, cooled, evaporated, or condensed.

The calculator is part of the Heat Transfer and Phase Change Thermodynamics Calculator category and is valuable for lab analysis, industrial system design, and thermal energy calculations.

Formula of Enthalpy of Water Calculator

1. Sensible Heat (Enthalpy in a Single Phase)

H = m × c × ΔT

• H = Enthalpy change (in joules or kilojoules)
• m = Mass of water (in kg)
• c = Specific heat capacity of water = 4186 J/kg·°C
• ΔT = Temperature change = Final temp − Initial temp (in °C)

This equation is used when water remains in one phase (solid, liquid, or gas) and only temperature changes.

2. Latent Heat (Phase Change Involved)

When water changes state (from ice to liquid, or liquid to vapor), use:

H = m × L

• L = Latent heat (in J/kg):
  • For vaporization (liquid to gas): L = 2,260,000 J/kg
  • For fusion (solid to liquid): L = 334,000 J/kg

Latent heat refers to energy absorbed or released during phase transitions without temperature change.

3. Total Enthalpy of Water (Including Phase Change and Heating)

If both phase change and temperature variation are involve:

Total H = (m × L) + (m × c × ΔT)

This is applied step by step:

• Use latent heat formula when water changes phase
• Use sensible heat formula for temperature changes before or after the phase change

Quick Reference Table

Here's a helpful table for common enthalpy scenarios involving 1 kg of water:

Process	Temp Change	Phase Change	Total Enthalpy (kJ)
Heating from 20°C to 80°C	60°C	None	251.2
Ice (0°C) to water (0°C)	0°C	Fusion	334.0
Boiling water at 100°C	0°C	Vaporization	2260.0
Ice to 50°C water	Fusion + 50°C	Yes	334.0 + 209.3 = 543.3
Steam (100°C) to 60°C water	−40°C	Condensation + cooling	2260.0 + 167.4 = 2427.4

This table can be used to estimate heating requirements and energy transfers in common thermal processes.

Example of Enthalpy of Water Calculator

Suppose you want to calculate how much energy is required to convert 2 kg of ice at 0°C into water at 50°C.

Step 1: Melt the ice

H₁ = m × L = 2 × 334,000 = 668,000 J = 668 kJ

Step 2: Heat the water from 0°C to 50°C

H₂ = m × c × ΔT = 2 × 4186 × 50 = 418,600 J = 418.6 kJ

Step 3: Total enthalpy

Total H = 668 + 418.6 = 1086.6 kJ

So, 1086.6 kJ of energy is required.

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