Which indicator can be used in the titration of strong acid and strong base

Options

A. Only phenoplphthalein
B. Only methyl orange
C. Eitehr of the two
D. Red litmus

Explanation

To determine which indicator can be used in the titration of a strong acid and a strong base, we can follow these steps:

### Step 1: Understand the nature of the titration
In a titration involving a strong acid (like hydrochloric acid, HCl) and a strong base (like sodium hydroxide, NaOH), the reaction will go to completion, resulting in the formation of water and a salt. The pH of the solution will change significantly at the equivalence point.

### Step 2: Identify the pH at the equivalence point
For the titration of a strong acid with a strong base, the equivalence point occurs at a pH of 7. This is because the resulting solution contains only the salt and water, which do not affect the pH significantly.

### Step 3: Choose an appropriate indicator
An appropriate indicator for this titration should have a color change at or near pH 7. Common indicators that fit this criterion include:
- **Phenolphthalein**: Changes color from colorless to pink around pH 8.2-10.0, which is slightly above the equivalence point but can still be used effectively.
- **Methyl orange**: Changes color from red to yellow in the pH range of 3.1-4.4, which is not suitable for strong acid-strong base titration since it changes color before reaching the equivalence point.

### Step 4: Conclusion
The best indicator to use in the titration of a strong acid and a strong base is **Phenolphthalein** because it provides a clear color change that can be observed as the pH approaches neutral.

### Summary
- **Indicator for strong acid-strong base titration**: Phenolphthalein