Review the equilibrium and choose the correct statement `HCIO_(4) + H_(2)O hArr H_(2)O^(+) CIO_(4)^(-)`

Options

A. `HCIO_(4)` is the conjugate base of `H_(2)O`
B. `H_(3)O^(+)` is the conjugate base of `H_(2)O`
C. `H_(2)O` is the conjugate acid of `H_(3)O^(+)`
D. `CIO_(4)^(-)` is the conjugate base of `HCIO_(4)`

Answer

To analyze the equilibrium reaction given in the question, we start with the following reaction:

\[ \text{HClO}_4 + \text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{ClO}_4^- \]

### Step 1: Identify the Acid and Base
In this reaction, we need to identify the acid and the base. HClO4 (perchloric acid) is a strong acid, which means it donates a proton (H+) to water (H2O).

**Hint:** Remember that acids donate protons, while bases accept them.

### Step 2: Identify the Conjugate Acid and Conjugate Base
When HClO4 donates a proton to water, it forms H3O+ (hydronium ion) and ClO4- (perchlorate ion). Here, H3O+ is the conjugate acid of water, and ClO4- is the conjugate base of HClO4.

**Hint:** The species formed after an acid donates a proton is its conjugate base, and the species formed after a base accepts a proton is its conjugate acid.

### Step 3: Analyze the Statements
Now, let's evaluate the statements provided in the question:

1. **HClO4 is the conjugate base of water.** - This statement is incorrect. HClO4 is an acid, not a base.

2. **H3O+ is the conjugate base of H2O.** - This statement is also incorrect. H3O+ is actually the conjugate acid of water.

3. **H2O is the conjugate acid of H3O+.** - This statement is incorrect because H2O is the base that forms H3O+.

4. **ClO4- is the conjugate base of HClO4.** - This statement is correct.

### Conclusion
The correct statement is that ClO4- is the conjugate base of HClO4.

**Final Answer:** ClO4- is the conjugate base of HClO4.