How can you tell an acid or base or neither from a chemical formula?

Answer 1

There is no hard and fast rule that can determine an acid/base solely from the formula.

Some can be derived from knowing the electronegativities and bonding behaviour of the elements concerned; some can be determined from knowing the electronic configurations of the elements; some can be told simply from memory i.e. if you know it's an acid/base then it's an acid/base.

Some cannot be derived at all from the formula; amphoteric substances for example, will be either basic or acidic depending on the conditions, and some substances will only act in certain ways in certain conditions too.

Answer 2

An acid typically starts with "H" like HCl, a base often ends in -OH like NaOH, and neither do not have distinctive patterns like H2O (water). The presence of hydrogen ions (H+) in a formula indicates acidity, while the presence of hydroxide ions (OH-) indicates basicity. Neutral compounds have equal numbers of positive and negative ions.