Skip to main content
Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 5

Refer to the figure to answer questions 4 and 5. The images are a molecular representation of three different substances, AX3, AY3, and AZ3, dissolved in water. (Water molecules are omitted for clarity.) What are the molar concentrations of A ions and X ions in a 0.500 M solution of AX3? (LO 4.7) (a) 0.500 M A and 0.500 M X (b) 0.500 M A and 0.167 M X (c) 1.500 M A and 0.500 M X (d) 0.500 M A and 1.500 M X

Verified step by step guidance
1
Identify the chemical formula of the compound AX3, which indicates that one formula unit of AX3 contains one A ion and three X ions.
Understand that when AX3 dissolves in water, it dissociates completely into its constituent ions: A and X.
Recognize that a 0.500 M solution of AX3 means there are 0.500 moles of AX3 per liter of solution.
Calculate the concentration of A ions: Since each formula unit of AX3 provides one A ion, the concentration of A ions is the same as the concentration of AX3, which is 0.500 M.
Calculate the concentration of X ions: Since each formula unit of AX3 provides three X ions, multiply the concentration of AX3 (0.500 M) by 3 to find the concentration of X ions.

Verified Solution

Video duration:
2m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (M). Understanding molarity is crucial for calculating the concentrations of ions in a solution, especially when dealing with ionic compounds that dissociate in water.
Recommended video:

Dissociation of Ionic Compounds

When ionic compounds dissolve in water, they dissociate into their constituent ions. For example, a compound AX3 will dissociate into one A ion and three X ions. This dissociation is essential for determining the molar concentrations of the individual ions in a solution, as it directly affects the total concentration of each ion present.
Recommended video:
Guided course
02:11
Ionic Compounds Naming

Stoichiometry of Dissolution

Stoichiometry involves the quantitative relationships between the amounts of reactants and products in a chemical reaction. In the context of dissolution, it helps in calculating the concentrations of ions based on the stoichiometric coefficients from the dissociation equation. For AX3, the stoichiometry indicates that for every mole of AX3, one mole of A and three moles of X are produced, guiding the concentration calculations.
Recommended video:
Guided course
01:16
Stoichiometry Concept