Essential Chemistry Formulas

Ever wondered how chemists measure exactly what they've got in their reactions? These key formulas are the building blocks you'll use constantly in chemistry calculations.

Rf values help you identify substances in chromatography: Rf = distance moved by spot ÷ distance moved by solvent. The closer to 1, the more the substance travelled with the solvent.

For concentration calculations, you've got two main approaches. When working with mass: concentration $g/dm³$ = mass of solute ÷ volume of solution. When dealing with moles: concentration $mol/dm³$ = moles of solute ÷ volume of solution.

Number of moles is fundamental to chemistry calculations: moles = mass ÷ Mr (relative molecular mass). You can also convert between concentration types using: concentration $mol/dm³$ = concentration $g/dm³$ ÷ Mr.

Quick Tip: Always check your units match the formula - convert cm³ to dm³ by dividing by 1000!

Percentage yield shows how efficient your reaction was: (actual yield ÷ theoretical yield) × 100. Meanwhile, atom economy measures how much of your reactants actually become useful product: (Mr of desired product ÷ total Mr of reactants) × 100.

For gas volume calculations, remember that one mole of any gas occupies 24 dm³ at room temperature and pressure: volume = moles × 24 dm³.