Chemistry

Fit a linear calibration curve from standards, calculate an unknown concentration, and check residuals and extrapolation.

Estimate uncalibrated radiocarbon age from carbon-14 left, percent modern carbon, or activity ratio, with BP and year display.

Find liquid ethylene density from temperature and pressure or from mass and volume, with state checks and unit conversions.

Calculate double bond equivalent from a molecular formula or atom counts, with steps and plain-English meaning.

Calculate degree of unsaturation from a molecular formula or atom counts. See atom counts, shown work, and formula checks.

Convert nitrogen to crude protein or switch crude protein between as-fed and dry matter basis for feed and forage analysis.

Balance complete combustion equations and find O2, air, CO2, H2O, and heat from fuel moles or grams.

Calculate stoichiometric air, actual air, lambda, and dry or wet flue-gas composition from fuel analysis and excess air.

Calculate COD in mg/L from titration data, add dilution correction, and check for chloride interference warnings.

Solve pressure difference, surface tension, or radius with the Young-Laplace equation for drops, bubbles, and curved surfaces.