Calculated Result
Submit the form to show your lattice enthalpy result, summary table, export buttons, and Plotly graph here.
Calculator Inputs
Select a method, enter your ionic data, and calculate a signed lattice enthalpy. The form stays in a single-column page layout, while inputs respond across screen sizes.
Result Summary Table
Your calculation summary table will appear here after submission.
Plotly Graph
The graph adapts to your selected method. Distance-based methods show sensitivity to radius changes, while the cycle method shows energy-step contributions.
Example Data Table
These sample rows are illustrative starting points for practice and classroom exploration. Replace them with literature values for your own compound.
| Compound | Method Focus | Key Input Set | Illustrative Values |
|---|---|---|---|
| NaCl | Born-Landé | z+, z−, r₀, M, n | 1, 1, 281.4 pm, 1.7476, 9 |
| MgO | Kapustinskii | ν, z+, z−, r₀, K, d | 2, 2, 2, 212 pm, 120200, 34.5 |
| CaF₂ | Kapustinskii | ν, z+, z−, r₀, K, d | 3, 2, 1, 252 pm, 120200, 34.5 |
| NaCl | Born-Haber | ΔHf°, atomization, dissociation, ΣIE, ΣEA | -411, 108, 121, 496, -349 |
Formulas Used
U = − [NA M z+ z− e2 / (4π ε0 r0)] × (1 − 1/n)
Use this when you know crystal geometry, the Madelung constant, the interionic distance, and a reasonable Born exponent.
U = − K ν |z+z−| / r0 × (1 − d / r0)
This is a fast estimate when full crystal-structure detail is missing. It often works well for comparing related ionic solids.
ΔHlatt = ΔHf° − (ΔHatom + ΔHdiss + ΣIE + ΣEA)
Keep every term in a consistent sign convention. Exothermic electron affinity should remain negative unless your source defines it differently.
This page reports a signed lattice enthalpy. Many textbooks publish the dissociation magnitude instead, so always confirm the convention before comparing values.
How to Use This Calculator
- Select the method that matches your available data.
- Enter the compound label for clearer exports and saved reports.
- Choose pm or Å for distance-style inputs.
- Fill every visible numeric field with literature or class values.
- Optionally add a reference lattice enthalpy for error checking.
- Press the calculate button to place the result above the form.
- Review the summary table, graph, and method-specific insights.
- Download CSV or PDF reports for lab notes, assignments, or revisions.
Frequently Asked Questions
1. What does lattice enthalpy describe?
Lattice enthalpy measures the energy change linked to forming or separating an ionic crystal. Stronger ionic attraction usually gives a larger magnitude and often higher melting behavior.
2. Why are some lattice enthalpy values negative?
A negative value usually represents crystal formation from gaseous ions, which releases energy. Some books report the opposite sign as a positive dissociation quantity instead.
3. When should I use the Born-Landé equation?
Use Born-Landé when you know crystal-specific inputs such as the Madelung constant, interionic distance, and a sensible Born exponent. It is more structure-aware than simpler estimates.
4. When is Kapustinskii more useful?
Kapustinskii is useful when crystal details are incomplete. It estimates lattice enthalpy from ionic charges, total ions per formula unit, and a radius sum.
5. What can cause large calculation errors?
Common issues include wrong sign conventions, poor radius estimates, inaccurate Born exponents, mismatched units, or mixing literature data that use different thermodynamic definitions.
6. Can this page handle polyatomic ions?
Yes, but the estimate quality depends on the method. Born-Haber can still work with good thermochemical data, while radius-based equations may become less reliable.
7. Why compare my answer with a reference value?
A reference value helps you judge whether assumptions are reasonable. Percent error is especially useful for assignments, model testing, and sensitivity analysis.
8. Does changing ionic distance matter a lot?
Yes. Small distance changes strongly affect electrostatic attraction, so lattice enthalpy can shift noticeably. The sensitivity graph helps you visualize that response.