The formation of a complex ion containing iron III and thiocyanate SCN- is affected by the pH of the solution. The complex ion formed in this case is Fe SCN n^3-n +, where n can be 1, 2, or 3.In acidic conditions, the concentration of H+ ions is high. The thiocyanate anion SCN- can react with H+ ions to form the weak acid HSCN. This reaction reduces the concentration of SCN- ions available to form the complex with iron III ions. As a result, the formation of the complex ion is less favored in acidic conditions.When the pH is changed from acidic to neutral conditions, the concentration of H+ ions decreases. This results in a decrease in the formation of HSCN and an increase in the concentration of SCN- ions. Consequently, the formation of the complex ion containing iron III and thiocyanate is favored in neutral conditions compared to acidic conditions.In summary, changing the pH from acidic to neutral conditions promotes the formation of the complex ion containing iron III and thiocyanate.