Question

Identify the following ions as acidic, neutral, or basic?

1) br-
2) i-
3) NO₂-
4) Mg₂⁺
5) nH₂NH₃
6) CO₂
7) c2h3O₂-
8) K⁺

Answer 1

Aqueous solutions of Br- and I- are neutral, NO₂- and C₂H₃O₂- are basic, NH₂NH₃+ and CO₂ are acidic, while Mg²⁺ and K+ are generally considered neutral.

Step-by-step explanation:

To determine whether aqueous solutions of the following ions are acidic, basic, or neutral, we must consider the parent acids and bases from which they are derived:

• Br- (Bromide ion) - from HBr, a strong acid; thus its conjugate base Br- is neutral.
• I- (Iodide ion) - from HI, a strong acid; its conjugate base I- is therefore neutral.
• NO₂- (Nitrite ion) - from HNO₂, a weak acid; thus its conjugate base NO₂- is basic.
• Mg²⁺ (Magnesium ion) - it's a cation from a strong base (Mg(OH)2), and does not hydrolyze, so it's often considered neutral but can slightly increase the pH of water due to water's natural hardness.
• NH₂NH₃+ (Hydrazinium ion) - from NH₂NH₃ (hydrazine), a weak base; thus its conjugate acid NH₂NH₃+ is acidic.
• CO₂ (Carbon Dioxide) - is not an ion, but when dissolved in water it forms carbonic acid (H₂CO₃), so it is acidic.
• C₂H₃O₂- (Acetate ion) - from CH₃COOH, a weak acid; thus its conjugate base C₂H₃O₂- is basic.
• K+ (Potassium ion) - from KOH, a strong base; thus its conjugate acid K+ is neutral.