(b) Can you identify which one between 0.10 mol ZnCl2 and 0.1M ZnCl2 contains more Zn2+ ion? Why?

Key Concepts

Molarity vs. Moles

Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. In this question, 0.1M ZnCl2 indicates a concentration of zinc chloride in a solution, while 0.10 mol ZnCl2 refers to a specific amount of zinc chloride without specifying the volume of the solution. Understanding the relationship between moles and molarity is crucial for determining the amount of Zn2+ ions present.

Dissociation of Ionic Compounds

Ionic compounds like ZnCl2 dissociate in solution into their constituent ions. For every mole of ZnCl2 that dissolves, it produces one mole of Zn2+ ions and two moles of Cl- ions. This dissociation is essential for calculating the total number of Zn2+ ions in a given solution, as it directly affects the concentration of the ions present.

Volume Consideration in Molarity

To compare the amount of Zn2+ ions in 0.10 mol ZnCl2 and 0.1M ZnCl2, one must consider the volume of the solution for the molarity case. If the volume of the 0.1M solution is not specified, it could be any volume, affecting the total moles of Zn2+. Thus, knowing the volume is critical to accurately assess which sample contains more Zn2+ ions.