1. What is the Enthalpy of Water Formula?

The enthalpy of water formula calculates the specific enthalpy of liquid water at a given temperature, using the reference point of 0°C where enthalpy is defined as 0 kJ/kg.

2. How Does the Calculator Work?

The calculator uses the enthalpy formula:

Where:

• \( h \) — Specific enthalpy (kJ/kg)
• \( T \) — Temperature (°C)
• 4.186 — Specific heat capacity of water (kJ/kg·°C)

Explanation: This formula calculates the energy content of water relative to its reference state at 0°C, using water's specific heat capacity.

3. Importance of Enthalpy Calculation

Details: Enthalpy calculations are essential in thermodynamics, HVAC systems, chemical engineering, and energy balance calculations for various processes involving water.

4. Using the Calculator

Tips: Enter the water temperature in degrees Celsius. The calculator will compute the specific enthalpy relative to 0°C reference point.

5. Frequently Asked Questions (FAQ)

Q1: Why is 0°C used as the reference point?
A: 0°C is commonly used as the reference point for water enthalpy calculations because it's the temperature where water freezes, providing a convenient baseline.

Q2: Does this formula account for phase changes?
A: No, this formula only calculates enthalpy for liquid water. Different formulas are needed for ice or steam enthalpy calculations.

Q3: How accurate is the specific heat value of 4.186 kJ/kg·°C?
A: This value is accurate for most engineering calculations, though the specific heat of water varies slightly with temperature (approximately 4.18-4.22 kJ/kg·°C).

Q4: Can this formula be used for seawater or other solutions?
A: No, this formula is specifically for pure water. Salinity and other dissolved substances affect the specific heat capacity and enthalpy calculations.

Q5: What are typical enthalpy values for water?
A: At room temperature (20°C), water has an enthalpy of about 83.7 kJ/kg. At boiling point (100°C), the enthalpy is approximately 418.6 kJ/kg.