Question

Ranking the following in order of decreasing acid strength. Select the best single answer: HCl, HClO, HNO2, HCN

Answer 1

The acids HCl, HNO2, HClO, and HCN can be ranked by their Ka values, indicating HCl as the strongest, followed by HNO2, HClO, and HCN as the weakest.

Step-by-step explanation:

To rank HCl, HClO, HNO2, and HCN in order of decreasing acid strength, we need to consider their ionization in water and acid ionization constants (Ka values). A higher Ka value indicates a stronger acid because it shows a greater tendency to donate protons in solution.

HCl is a strong acid and its Ka value can be inferred to be significantly higher than the other acids in this list, which are all weak. When comparing the weak acids, we use the provided Ka values:

• For HNO2 (nitrous acid), Ka = 4.6 × 10-4
• For HCN (hydrocyanic acid), Ka = 1.8 × 10-5

Since HClO (hypochlorous acid) is not listed with a specific Ka value in the provided information, we should rely on other sources or general chemistry knowledge, which typically places HClO as a weaker acid than HNO2 but stronger than HCN.

Therefore, the correct order from most acidic to least acidic is HCl > HNO2 > HClO > HCN.

Answer 2

The compounds HCl, HNO2, HClO, and HCN are ranked in order of decreasing acid strength with HCl being the strongest, followed by HNO2, then HClO, and HCN being the weakest.

Step-by-step explanation:

To rank the given compounds HCl, HClO, HNO2, and HCN in order of decreasing acid strength, one needs to understand the concept of acid dissociation and the strength of acids. The stronger an acid, the more completely it ionizes in a solution. Based on established acid strength trends and acid-ionization constants (Ka values), we can arrange these acids from strongest to weakest as follows:

1. HCl (Hydrochloric acid)
2. HNO2 (Nitrous acid)
3. HClO (Hypochlorous acid)
4. HCN (Hydrocyanic acid)

HCl is known to be a strong acid that ionizes completely in water, hence it tops the list. HNO2 is a weak acid but has a higher Ka value compared to HClO and HCN. HCN is the weakest among the given acids with the lowest Ka value.