Which of the following solutions contains the greatest number of ions?

A. 300.0 mL of 0.10 M CaCl2
B. 400.0 mL of 0.10 M NaCl
C. 200.0 mL of 0.10 M FeCl3
D. 800.0 mL of 0.10 M sucrose

Answer : The correct option is, (A) 300.0 mL of 0.10 M CaCl₂

Explanation :

(a) 300.0 mL of 0.10 M CaCl₂

The dissociation reaction will be:

To calculate the number of moles of CaCl₂ as :

As, 1 mole of CaCl₂ contains ions = 3

So, 0.03 mole of CaCl₂ contains ions = 0.03 × 3 = 0.09 ions.

(b) 400.0 mL of 0.10 M NaCl

The dissociation reaction will be:

To calculate the number of moles of NaCl as :

As, 1 mole of NaCl contains ions = 2

So, 0.04 mole of NaCl contains ions = 0.04 × 2 = 0.08 ions.

(c) 200.0 mL of 0.10 M FeCl₃

The dissociation reaction will be:

To calculate the number of moles of FeCl₃ as :

As, 1 mole of FeCl₃ contains ions = 4

So, 0.02 mole of FeCl₃ contains ions = 0.02 × 4 = 0.08 ions.

(d) 800.0 mL of 0.10 M sucrose

The dissociation of sucrose is not possible because it is a non-electrolyte.

To calculate the number of moles of sucrose as :

As, 1 mole of sucrose contains ions = 1

So, 0.08 mole of sucrose contains ions = 0.08 × 1 = 0.08 ions.

Hence, the solutions contains the greatest number of ions is, 300.0 mL of 0.10 M CaCl₂

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