Question

Which of the following solution has highest amount of solute?

• A. 1.0 L of 0.25 M \( \text{Na}_2\text{CO}_3 \)
• B. 0.25 L of 0.2 M \( \text{Na}_2\text{SO}_4 \)
• C. 0.5 L of 1.0 M \( \text{KMnO}_4 \)
• D. 0.75 L of 0.5 M \( (\text{NH}_2)_2\text{CO} \)

Hint:

Start by calculating moles (\( M \times V \)). Often the option with the highest moles also has the highest mass unless molar masses are drastically different.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:

"Amount of solute" usually refers to the mass or number of moles. Since different compounds are listed, we first calculate moles. If required, mass can be obtained using molar mass. Generally, the product M × V gives the number of moles.

Step 2: Key Formula or Approach:

n = M × V (where M = molarity, V = volume in liters)

Step 3: Detailed Explanation:

(A)
n = 0.25 × 1.0 = 0.25 mol
Mass of Na2CO3 (106 g/mol):
0.25 × 106 = 26.5 g

(B)
n = 0.2 × 0.25 = 0.05 mol
Mass of Na2SO4 (142 g/mol):
0.05 × 142 = 7.1 g

(C)
n = 1.0 × 0.5 = 0.5 mol
Mass of KMnO4 (158 g/mol):
0.5 × 158 = 79 g

(D)
n = 0.5 × 0.75 = 0.375 mol
Mass of Urea (60 g/mol):
0.375 × 60 = 22.5 g

Comparison:

Moles:
(C) 0.5 > (D) 0.375 > (A) 0.25 > (B) 0.05

Mass:
(C) 79 g > others

Thus, option (C) has the highest amount of solute (both in moles and mass).

Step 4: Final Answer:

0.5 L of 1.0 M KMnO4 has the highest amount.