Question

In the following question, a positive and a negative radical is listed. Using the criss-cross method, write the formula for the compound that is formed and name the compound.

K⁺¹ OH^-1

Answer 1

Step-1: Identify the acidic and basic radicals or positive and negative ions:

• Positive ion or cation or basic radical: K⁺¹
• Negative ion or anion or acidic radical: OH^-1

Step-2: Write the valency of the ion:

• Valency is written as a positive or negative charge on the ion as a superscript on the right hand side.
• Valency of K⁺¹ is 1 Valency of OH^-1 is 1

Step-3: Write the valency of the ion below or above its symbol without the + or - sign:

Symbol of radical K OH

Valency of the radical 1 1

Step-4: Transpose the valency by criss-cross:

• Criss-cross multiplication is a method where the valency of a cation is written as a subscript of anion and vice-versa.

$$\begin{gathered} \mathrm{K}\mathrm{OH} \\ \searrow \swarrow \\ 11 \end{gathered}$$

Step-5: Write the outcome of criss-cross and simplify by dividing using a common factor if needed

• K₁(OH)₁ or KOH

Step-6: Write the chemical formula and chemical name

• Cation is written first followed by the anion.
• The chemical formula of the compound is KOH.
• Name of the cation is written followed by the anion.
• K is written as Potassium and OH as hydroxide.
• The chemical name of the compound is Potassium hydroxide.