Skip to main content
Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 92d

The accompanying photo shows the reaction between a solution of Cd(NO3)2 and one of Na2S. (d) Is this a redox reaction?

Verified step by step guidance
1
Identify the reactants and products in the reaction: Cd(NO_3)_2 and Na_2S react to form CdS and NaNO_3.
Determine the oxidation states of each element in the reactants and products. For example, in Cd(NO_3)_2, Cd is +2 and in Na_2S, S is -2.
Check if there is a change in oxidation states for any of the elements from reactants to products. In CdS, Cd is still +2 and S is still -2, indicating no change.
Since there is no change in oxidation states, this indicates that no electrons are transferred between the elements.
Conclude that the reaction is not a redox reaction, as there is no change in oxidation states of the elements involved.

Verified video answer for a similar problem:

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

Key Concepts

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

Redox Reactions

Redox reactions, or reduction-oxidation reactions, involve the transfer of electrons between two species. In these reactions, one substance is oxidized (loses electrons) while another is reduced (gains electrons). Identifying whether a reaction is a redox process requires analyzing the oxidation states of the elements involved before and after the reaction.
Recommended video:
Guided course
03:12
Identifying Redox Reactions

Oxidation States

Oxidation states (or oxidation numbers) are a way to keep track of electrons in chemical reactions. They indicate the degree of oxidation of an atom in a compound, helping to determine whether an atom has gained or lost electrons. In the context of the given reaction, calculating the oxidation states of cadmium (Cd) and sulfur (S) will clarify if any changes occur, indicating a redox reaction.
Recommended video:
Guided course
02:42
Oxidation Numbers

Ionic Compounds and Solubility

Ionic compounds, such as Cd(NO3)2 and Na2S, dissociate into their constituent ions when dissolved in water. Understanding the solubility of these compounds is crucial, as it affects the reaction dynamics. The formation of precipitates or soluble ions can influence whether a redox reaction occurs, as the physical state of the reactants can determine the pathway of the reaction.
Recommended video:
Guided course
02:30
Soluble Ionic Solutes