Second or third year undergraduate

Analytical chemistry practical

Calibration, statistics, and instrument maths: standard curves, outlier tests, significance, chromatography transfer, and the reference tables an analytical course keeps reaching for.

11 calculators, in the order the course uses them. Every one shows its working, flags the hazards, and keeps working offline once the page has loaded. Free, and no account is needed.

Start with Molar mass, grams and moles All topics and reference tables

In course order

What this practical calculates

1. Molar mass, grams and moles

Type an element or formula (Sb, NaCl, C6H12O6) and convert grams to moles. Molar mass is computed from cited atomic weights.

How it works · Practice problems · n = m / MW

2. Standard curve

Fit a linear or quadratic standard curve (Bradford, BCA, ELISA) and read unknowns.

How it works · signal = slope x conc + intercept

3. Beer-Lambert (absorbance to concentration)

Concentration from absorbance, any extinction-coefficient convention.

How it works · Practice problems · A = ε · c · l

4. Dixon's Q outlier test

Flag a suspect replicate (3 to 10 values). Advisory only, never auto-deleted.

How it works · Q = gap / range; flag if Q > Q_crit

5. Significance quick-test (t)

Welch's t-test for two groups: p-value, effect size, and a plain verdict.

How it works · t = (x̄_A − x̄_B) / √(s_A²/n_A + s_B²/n_B)

6. HPLC method transfer

Scale flow, injection, and gradient between columns, with void volume and dead time.

How it works · F₂ = F₁(d₂/d₁)²(dp₁/dp₂)

7. MS adduct m/z calculator

Formula or mass to adduct m/z, and reverse-match an observed peak by ppm.

How it works · Practice problems · m/z = (M·n + adduct) / z

8. NMR impurity finder

Identify a 1H peak from its shift, or look up where a known compound appears (Fulmer table).

How it works · nearest tabulated δ in the chosen solvent

9. Ionic strength and activity

I = ½ Σ cz², plus activity coefficients (Debye-Huckel to Davies).

How it works · I = ½ Σ cᵢzᵢ²

10. Pipette calibration (ISO 8655)

Turn weighed water masses into accuracy and precision against the nominal volume.

How it works · V = mass × Z

11. Legacy unit converter

Convert Torr, atm, psi, cal, eV, poise, dyne and other legacy units to SI.

How it works · value × factor(from) ÷ factor(to)

Worth telling students once

The mistakes this practical produces every year

Discarding an outlier needs a stated test and a stated confidence level, not a judgement. The Dixon Q calculator reports both.

A pipette that has never been checked gravimetrically is an unquantified error in every result that used it. The ISO 8655 calculator turns a balance reading into accuracy and precision figures.

For the person running the course

If you want this page named for your course

What it costs

Nothing, for you and for your students, permanently. There is no licence to sign, no account for students to create, no data to hand over, and nothing for your IT department to approve or install.

What you would get

A page named for your course, with your calculations in your order and your conventions, at a stable URL you can paste into your course management system once and reuse every year.

What we would like back

To be told when it is wrong. If a value, a convention, or a hazard note does not match how your course teaches it, that is a bug worth fixing.

Ask for a page for your course

The honest caveat

Aliquot is an educational aid, not a safety authority and not a certified instrument. Students should verify critical values and follow the safety data sheet and your institution's protocols.

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