What this calculator does
Combustion analysis works out finds the empirical formula of a CHO compound from the CO2 and H2O produced by combustion. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulamC = mCO2×(MC/MCO2); mH = mH2O×(2MH/MH2O); mO = sample mass − mC − mH; moles = mass/molar mass; divide each by the smallest to get whole-number ratios
The inputs explained
| Field | What to enter |
|---|---|
| Sample mass (g) | A number, measured in g. Starts at 0.5. |
| CO2 produced (g) | A number, measured in g. Starts at 1.466. |
| H2O produced (g) | A number, measured in g. Starts at 0.6. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with sample mass
Every other input is held at the calculator’s starting values while sample mass varies. Select any row to load that scenario into the calculator.
How the answer changes with sample mass