Most effective ion to coagulate a negative sol is:

Options

A. `PO_(4)^(3-)`
B. `AI^(3+)`
C. `Ba^(2+)`
D. `K^(+)`

Answer

To determine the most effective ion to coagulate a negative sol, we can use the Hardy-Schulze rule, which provides a systematic approach to understanding coagulation in colloidal systems. Here’s a step-by-step solution:

### Step 1: Understand the Charge of the Sol
- A negative sol contains negatively charged particles. To coagulate (or destabilize) this sol, we need to introduce ions that carry a positive charge.

**Hint:** Identify the charge of the sol to determine the type of ions needed for coagulation.

### Step 2: Identify the Relevant Ions
- The question provides several options for ions that could potentially coagulate the negative sol. We need to focus on the positive ions (cations) since they will interact with the negatively charged particles.

**Hint:** Look at the options given and filter them based on their charge.

### Step 3: Apply Hardy-Schulze Rule
- According to the Hardy-Schulze rule, the coagulating power of an electrolyte is directly proportional to the valency of the active ions. This means that ions with higher valency will be more effective at coagulating the sol.

**Hint:** Remember that higher valency means stronger coagulation power.

### Step 4: Evaluate the Options
- Let’s evaluate the options based on their valency:
1. **Al³⁺**: This ion has a valency of 3.
2. **Ba²⁺**: This ion has a valency of 2.
3. **K⁺**: This ion has a valency of 1.

**Hint:** Compare the valencies of the cations provided in the options.

### Step 5: Determine the Most Effective Ion
- Since Al³⁺ has the highest valency (3), it will be the most effective ion to coagulate the negative sol according to the Hardy-Schulze rule.

**Hint:** The ion with the highest positive charge (valency) will be the most effective for coagulation.

### Conclusion
- Therefore, the most effective ion to coagulate a negative sol is **Al³⁺**.

**Final Answer:** Al³⁺ (option 2) is the correct answer.