Questions: Ion concentration refers to the molar concentration of an ion in solution. It may be identical to, or greater or less than, the molar concentration of the compound containing the ion that was used to make the solution. For soluble salts, the molarity of a particular ion is equal to the molarity of that compound times the subscript for that ion. For example, 1 M of AlCl3 is 1 M in Al3+ and 3 M in Cl-. 1 M of (NH4)2SO4 is 2 M in NH4+ and 1 M in SO42-.
Part B
If CaCl2 is dissolved in water, what can be said about the concentration of the Ca2+ ion?
It has the same concentration as the Cl ion. Hs concentration is half that of the Cl- ion. Its concentration is twice that of the Cl- ion. Its concentration is one-third that of the Cl- ion.
Transcript text: Ion concentration refers to the molar concentration of an ion in solution. It may be identical to, or greater or less than, the molar concentration of the compound containing the ion that was used to make the solution. For soluble salts, the molarity of a particular ion is equal to the molarity of that compound times the subscript for that ion. For example, 1 M of $\mathrm{AlCl}_{3}$ is 1 M in $\mathrm{Al}^{3+}$ and 3 M in $\mathrm{Cl}^{-} .1 \mathrm{M}$ of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ is 2 M in $\mathrm{NH}_{4}{ }^{+}$and 1 M in $\mathrm{SO}_{4}{ }^{2-}$.
Part B
If $\mathrm{CaCl}_{2}$ is dissolved in water, what can be said about the concentration of the $\mathrm{Ca}^{2+}$ ion?
View Available Hint(s)
It has the same concentration as the $\mathbf{C l}$ ion.
Hs concentration is half that of the $\mathrm{Cl}^{-}$ion.
Its concentration is twice that of the $\mathrm{Cl}^{-}$ion.
Its concentration is one-third that of the $\mathrm{Cl}^{-}$ion.
Solution
Solution Steps
Step 1: Analyze the Chemical Formula
When CaCl₂ dissolves in water, it dissociates into its constituent ions: one Ca²⁺ ion and two Cl⁻ ions. This is represented by the equation: CaCl₂ → Ca²⁺ + 2Cl⁻
Step 2: Relate Ion Concentrations
The equation shows that for every 1 mole of CaCl₂ that dissolves, 1 mole of Ca²⁺ ions and 2 moles of Cl⁻ ions are produced. Therefore, the concentration of Cl⁻ ions will be twice the concentration of Ca²⁺ ions.
Step 3: Determine the Relationship
Since the chloride ion concentration is twice the calcium ion concentration, the calcium ion concentration is half the chloride ion concentration.