Molar mass of acids

Acids give hydrogen ions in water. In the laboratory they are the first solutions a student learns to make up by molarity, so their molar masses are used again and again in titration sums.

When a question gives the volume and molarity of an acid, molar mass is what turns the answer into grams. Remember that hydrochloric, nitric and sulphuric acid in bottles are solutions: the molar mass belongs to the pure compound, and the label gives the concentration. An acid that can give two or three hydrogen ions, such as sulphuric or phosphoric acid, reacts with two or three moles of alkali for each mole of acid.

This page lists 12 acids with their formulas and molar masses, lightest first. The lightest here is hydrogen fluoride at 20.01 g/mol and the heaviest is citric acid at 192.12 g/mol. Tap a name for the full working, the percentage of each element and worked examples.

Which values? This site uses the abridged standard atomic weights published by IUPAC (CIAAW), read on 12 November 2026. Your textbook or question paper may round them differently, for example H = 1 and O = 16, so its answer can differ slightly. In an exam, use the values the paper gives.

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Type any formula into the calculator. It handles brackets and water of crystallisation and shows the same working as these pages. The method by hand is on the step by step page.

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