Which of the following molecules is capable of generating the greatest osmotic pressure ?

Options

A. (a) 300 mM glucose
B. 300 mM urea
C. 300 `mMNaCl`
D. 300 mM `CaCl_(2)`

Answer

To determine which molecule generates the greatest osmotic pressure, we can use the formula for osmotic pressure (π):

\[ \pi = iCRT \]

Where:
- \( \pi \) = osmotic pressure
- \( i \) = van't Hoff factor (number of particles the solute dissociates into)
- \( C \) = concentration of the solution
- \( R \) = universal gas constant (constant)
- \( T \) = temperature in Kelvin (constant)

### Step-by-Step Solution:

1. **Identify the van't Hoff factor (i)**:
- For **glucose** (C6H12O6): It does not dissociate in solution, so \( i = 1 \).
- For **urea** (NH2CONH2): It also does not dissociate, so \( i = 1 \).
- For **sodium chloride (NaCl)**: It dissociates into Na⁺ and Cl⁻, so \( i = 2 \).
- For **calcium chloride (CaCl2)**: It dissociates into Ca²⁺ and 2 Cl⁻, so \( i = 3 \).

2. **Given concentration (C)**:
- The concentration for all solutes is given as 300 millimoles (or 0.3 moles).

3. **Calculate osmotic pressure for each solute**:
- For **glucose**:
\[ \pi = iCRT = 1 \times 300 \times RT = 300RT \]
- For **urea**:
\[ \pi = iCRT = 1 \times 300 \times RT = 300RT \]
- For **sodium chloride (NaCl)**:
\[ \pi = iCRT = 2 \times 300 \times RT = 600RT \]
- For **calcium chloride (CaCl2)**:
\[ \pi = iCRT = 3 \times 300 \times RT = 900RT \]

4. **Compare the osmotic pressures**:
- Glucose: \( 300RT \)
- Urea: \( 300RT \)
- Sodium Chloride: \( 600RT \)
- Calcium Chloride: \( 900RT \)

5. **Conclusion**:
- The greatest osmotic pressure is generated by calcium chloride (CaCl2) with a value of \( 900RT \).

### Final Answer:
The molecule capable of generating the greatest osmotic pressure is **Calcium Chloride (CaCl2)**.