Question

How do you determine the formula for aluminium hydroxide?

Answer 1

Hint As we know that hydroxide has the oxidation state of -1, that is it is denoted by the symbol $O{{H}^{-}}$. And we can write the formula for aluminium hydroxide on the basis of this, which is a balanced oxidation state.

Complete Step by step solution:
- As we know that oxidation states basically indicate the hypothetical charge on the atom that is given on the basis of gain of electrons or loss of electrons to form a chemical bond.
- It is found that the oxidation number of an atom is equal to the total number of electrons that is added to the element or removed from an element to reach the present state.
- As we know that aluminium hydroxide is ionic in nature and we can write it in dissociated as well as in balanced form as: $A{{l}^{3+}}$ and $O{{H}^{-}}$ .
- It is found that ionic bonds are formed when the charges between non-metal anion and metal cation are equal and opposite. We can say that charge of aluminium that is +3 goes to hydroxide while its charge of -1 will go to aluminium.
- Therefore, on the basis of this information we can write the formula for aluminium hydroxide as $Al{{\left( OH \right)}_{3}}$, based on their oxidation states.

Hence, we can conclude that we can write the formula for $Al{{\left( OH \right)}_{3}}$.

Note: We should note that while writing the chemical formula we must know in which form the atom exists whether di, mono or triatomic, and we must also know the oxidation states. All these facts will help us to get the correct answer.