What substances do not contain acids?

- Pure water: Water in its pure form does not contain acids. It has a neutral pH of 7.

- Bases: Bases are substances that have a pH greater than 7. They are the opposite of acids and do not contain acidic properties.

- Salts: Salts are ionic compounds formed by the reaction between an acid and a base. They do not possess acidic properties and typically have a neutral or basic pH.

- Pure metals: Metals in their elemental form do not contain acids. They may react with acids to form metal salts, but the metals themselves are not acidic.

- Non-acidic gases: Gases such as oxygen (O2), nitrogen (N2), carbon dioxide (CO2), and methane (CH4) are not acidic. They do not release H+ ions when dissolved in water and have a neutral or slightly basic pH.

- Certain organic compounds: Some organic compounds, such as fats, oils, and sugars, do not have acidic properties. They may undergo chemical reactions under certain conditions, but they are not considered acids.

It is important to note that the absence of acids in a substance does not necessarily mean it is safe or harmless. Some non-acidic substances can still be toxic or corrosive. Always refer to the material safety data sheet (MSDS) or consult an expert before handling any chemical substance.