70% ethanol disinfects more effectively than higher concentrations because the water helps denature proteins. Make it by diluting concentrated ethanol; amounts below are for diluting 95% ethanol per litre of final solution.
Ingredient amounts below update automatically.
Ingredients
| Component | Amount | Note |
|---|---|---|
| 95% ethanol | 737 mL | gives 70% v/v; use 700 mL if starting from 100% |
| Deionised water | 263 mL | to final volume |
Method
- Measure the ethanol into a container or graduated cylinder.
- Add deionised water up to the final volume and mix.
- From absolute (100%) ethanol, use 700 mL ethanol plus water to 1 L instead.
- Store in a sealed, labelled container away from ignition sources.
Notes & safety
Ethanol is flammable; prepare away from open flames and store appropriately. Mixing ethanol and water is slightly volume-contracting, so make up to the final volume after combining rather than adding fixed volumes blindly.
Consult the Safety Data Sheet for each reagent and follow your institution's protocols. Wear appropriate PPE.
Related guides: Percent Concentration Solutions · How to Prepare a Solution of a …
Equipment for this prep
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Volumetric Flask Set (Class A)
Class A borosilicate flasks for making solutions to an exact volume.
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