The `pK_(a)` of acteylsalicylic acid (aspirin) is `3.5`. The pH of gastric juice in human stomach is about `2-3` and the pH in the small intestine is about 8. Aspirin will be:

Options

A. Unionised in the small intestine and in the stomach.
B. Completely ionised in the small intestine and in the stomach.
C. Ionised in the stomach and alomost unionised in the small intestine.
D. Ionised in small intestine and almost unionised in the stomach.

Explanation

To determine the state of aspirin in different pH environments, we can follow these steps:

### Step 1: Understand the pKa and pH relationship
- The pKa of acetylsalicylic acid (aspirin) is given as 3.5. The pKa is the pH at which half of the acid is ionized and half is unionized.
- If the pH is lower than the pKa, the acid will be predominantly in its unionized form. If the pH is higher than the pKa, the acid will be predominantly ionized.

### Step 2: Analyze the pH of gastric juice
- The pH of gastric juice is about 2-3, which is acidic.
- Since the pH (2-3) is lower than the pKa (3.5), aspirin will be mostly unionized in the stomach.

### Step 3: Analyze the pH of the small intestine
- The pH in the small intestine is about 8, which is basic.
- Since the pH (8) is higher than the pKa (3.5), aspirin will be mostly ionized in the small intestine.

### Step 4: Conclusion
- Therefore, in the stomach (acidic environment), aspirin is predominantly unionized, while in the small intestine (basic environment), it is predominantly ionized.

### Final Answer
Aspirin will be mostly unionized in the stomach and mostly ionized in the small intestine.

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