Molar Enthalpy Calculator for Water

Molar Enthalpy Formula:

\[ \Delta H_m = \frac{m \times c \times \Delta T}{n} \]

Mass:

Specific Heat Capacity:

J/kg·K

Temperature Change:

Moles:

mol

Molar Enthalpy (J/mol):

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1. What is Molar Enthalpy?

Definition: Molar enthalpy is the amount of energy (in joules) absorbed or released per mole of substance during a thermodynamic process.

Purpose: This calculator helps determine the molar enthalpy change of water when its temperature changes.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \Delta H_m = \frac{m \times c \times \Delta T}{n} \]

Where:

\( \Delta H_m \) — Molar enthalpy (J/mol)
\( m \) — Mass of water (kg)
\( c \) — Specific heat capacity (4186 J/kg·K for water)
\( \Delta T \) — Temperature change (K)
\( n \) — Number of moles (mol)

Explanation: The calculator multiplies mass, specific heat, and temperature change, then divides by moles to get energy per mole.

3. Importance of Molar Enthalpy Calculation

Details: Molar enthalpy is crucial in thermochemistry for understanding energy changes in chemical reactions and physical processes.

4. Using the Calculator

Tips: Enter the mass of water in kg, specific heat capacity (default 4186 J/kg·K for water), temperature change in Kelvin, and number of moles. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is specific heat capacity 4186 J/kg·K?
A: This is the specific heat capacity of liquid water at standard conditions.

Q2: How do I calculate moles of water?
A: Moles = mass (kg) × 1000 ÷ molar mass (18.015 g/mol for water).

Q3: What if I have grams instead of kg?
A: Convert grams to kg by dividing by 1000 before entering the mass value.

Q4: Can I use this for other substances?
A: Yes, but you must change the specific heat capacity to match your substance.

Q5: What does a negative ΔH_m mean?
A: A negative value indicates an exothermic process (heat released).