/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 38 Which two of the following react... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 5: Problem 38

Which two of the following reactions are oxidationreduction reactions? Explain your answer briefly. Classify the remaining reaction. (a) \(\operatorname{Cd} \mathrm{Cl}_{2}(\mathrm{aq})+\mathrm{Na}_{2} \mathrm{S}(\mathrm{aq}) \longrightarrow \operatorname{CdS}(\mathrm{s})+2 \mathrm{NaCl}(\mathrm{aq})\) (b) \(2 \mathrm{Ca}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{CaO}(\mathrm{s})\) (c) \(4 \mathrm{Fe}(\mathrm{OH})_{2}(\mathrm{s})+2 \mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{O}_{2}(\mathrm{g}) \longrightarrow 4 \mathrm{Fe}(\mathrm{OH})_{3}(\mathrm{aq})\)

Short Answer

Expert verified
Reactions (b) and (c) are redox reactions. Reaction (a) is a double displacement reaction.

Step by step solution

01

Identify reaction type for reaction (a)

In reaction (a), \[ \operatorname{Cd} \mathrm{Cl}_{2}(\mathrm{aq}) + \mathrm{Na}_{2}\mathrm{S}(\mathrm{aq}) \longrightarrow \operatorname{CdS}(\mathrm{s}) + 2\mathrm{NaCl}(\mathrm{aq}) \]both the reactants and products involve ionic compounds. To identify if it's an oxidation-reduction reaction, we should check if the oxidation states of any elements change from reactants to products. Cd in CdCl2 is +2 and remains +2 in CdS; S in Na2S is -2 and remains -2 in CdS, while Na and Cl remain +1 and -1 respectively in both sides of the reaction. Hence, this is a double displacement reaction.
02

Check reaction type for reaction (b)

In reaction (b), \[ 2 \mathrm{Ca}(\mathrm{s}) + \mathrm{O}_{2}(\mathrm{g}) \longrightarrow 2\mathrm{CaO}(\mathrm{s}) \]Calcium, initially with an oxidation state of 0, forms calcium oxide where it has an oxidation state of +2. Oxygen, initially 0, becomes -2 in CaO. Since oxidation states change, this is an oxidation-reduction (redox) reaction.
03

Analyze reaction type for reaction (c)

In reaction (c), \[ 4 \mathrm{Fe}(\mathrm{OH})_{2}(\mathrm{s}) + 2 \mathrm{H}_{2}\mathrm{O}(\ell) + \mathrm{O}_{2}(\mathrm{g}) \longrightarrow 4 \mathrm{Fe}(\mathrm{OH})_{3}(\mathrm{aq}) \]Fe(OH)2 contains iron in the +2 state, which gets oxidized to +3 in Fe(OH)3, whereas oxygen is reduced from 0 to -2 upon forming new hydroxide ions. This indicates a redox process.
04

Classify the remaining reactions

Having identified that reactions (b) and (c) are redox reactions, reaction (a), due to lack of change in oxidation states, is classified as a double displacement or metathesis reaction.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Redox Reaction
Oxidation-reduction reactions, commonly known as redox reactions, are processes where electrons are transferred between substances. During these reactions, one substance undergoes oxidation (loses electrons), while another is reduced (gains electrons). A change in oxidation states is the hallmark of redox reactions.
In the context of the exercise provided, reactions (b) and (c) exemplify redox reactions:
  • In reaction (b), calcium ( Ca) is oxidized from an oxidation state of 0 to +2 as it forms CaO, while oxygen (O2) is reduced from 0 to -2 in CaO.
  • For reaction (c), iron in Fe(OH)2 changes from an oxidation state of +2 to +3 in Fe(OH)3, while oxygen is reduced.
Recognizing these electron transfers is crucial in classifying reactions as redox processes.
Double Displacement Reaction
Double displacement reactions, also known as metathesis reactions, involve the exchange of ions between two compounds to form new compounds. In these reactions, each compound swaps components, but the oxidation state of the involved elements does not change.
In the exercise, reaction (a) is identified as a double displacement reaction:
  • Cadmium chloride ( CdCl2) and sodium sulfide ( Na2 S) exchange ions to form cadmium sulfide ( CdS) and sodium chloride ( NaCl).
  • No change in the oxidation states of cadmium, sulfur, sodium, or chlorine occurs throughout the reaction.
This lack of electron transfer differentiates double displacement reactions from redox reactions, proving that the ionic bonds are simply rearranged.
Oxidation States
The concept of oxidation states is key to understanding chemical reactions. An oxidation state (or number) refers to the hypothetical charge an atom would have if all bonds to it were ionic. This concept helps in identifying redox reactions by indicating where electron transfers occur.
For each element:
  • Metals typically have positive oxidation states as they lose electrons.
  • Non-metals tend to have negative oxidation states as they gain electrons.
In reaction (b), for example, calcium changes from 0 in its elemental form to +2 in CaO, indicating electron loss. This change marks oxidation. Meanwhile, in reaction (c), iron's oxidation state shifts from +2 to +3 in the formation of Fe(OH)3, showcasing intricate changes typical in redox reactions.
By tracking oxidation state changes, chemists determine how atoms interact and recognize the nature of chemical processes.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Balance the following reactions and then classify each as a precipitation, acid-base, or gas-forming reaction. (a) \(\mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{aq})+\mathrm{HCl}(\mathrm{aq}) \longrightarrow \mathrm{BaCl}_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)\) (b) \(\mathrm{HNO}_{3}(\mathrm{aq})+\mathrm{CoCO}_{3}(\mathrm{s}) \longrightarrow\) \(\operatorname{Co}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)+\mathrm{CO}_{2}(\mathrm{g})\) (c) \(\mathrm{Na}_{3} \mathrm{PO}_{4}(\mathrm{aq})+\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq}) \longrightarrow\) \(\mathrm{Cu}_{3}\left(\mathrm{PO}_{4}\right)_{2}(\mathrm{s})+\mathrm{NaNO}_{3}(\mathrm{aq})\)

To analyze an iron-containing compound, you convert all the iron to \(\mathrm{Fe}^{2+}\) in aqueous solution and then titrate the solution with standardized \(\mathrm{KMnO}_{4}\). The balanced, net ionic equation is \(\mathrm{MnO}_{4}^{-}(\mathrm{aq})+5 \mathrm{Fe}^{2+}(\mathrm{aq})+8 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow\) $$\mathrm{Mn}^{2+}(\mathrm{aq})+5 \mathrm{Fe}^{3+}(\mathrm{aq})+4 \mathrm{H}_{2} \mathrm{O}(\ell) $$ A \(0.598-\mathrm{g}\) sample of the iron-containing compound requires \(22.25 \mathrm{mL}\) of \(0.0123 \mathrm{M} \mathrm{KMnO}_{4}\) for titration to the equivalence point. What is the mass percent of iron in the sample?

Potassium hydrogen phthalate, \(\mathrm{KHC}_{8} \mathrm{H}_{4} \mathrm{O}_{4},\) is used to standardize solutions of bases. The acidic anion reacts with strong bases according to the following net ionic equation: \(\mathrm{HC}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{-}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \longrightarrow \mathrm{C}_{8} \mathrm{H}_{4} \mathrm{O}_{4}^{2-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\ell)\) If a \(0.902-\mathrm{g}\) sample of potassium hydrogen phthalate is dissolved in water and titrated to the equivalence point with \(26.45 \mathrm{mL}\) of \(\mathrm{NaOH}\), what is the molar concentration of the NaOH?

A You place \(2.56 \mathrm{g}\) of \(\mathrm{CaCO}_{3}\) in a beaker containing 250\. mL of 0.125 M HC1 (Figure 5.5). When the reaction has ceased, does any calcium carbonate remain? What mass of \(\mathrm{CaCl}_{2}\) can be produced? $$\mathrm{CaCO}_{3}(\mathrm{s})+2 \mathrm{HCl}(\mathrm{aq}) \longrightarrow \mathrm{CaCl}_{2}(\mathrm{aq})+\mathrm{CO}_{2}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\ell)$$

Balance these reactions and then classify each one as a precipitation, acid- base, or gas-forming reaction. Show states for the products \((\mathrm{s}, \ell, \mathrm{g}, \mathrm{aq}),\) and write the net ionic equation. (a) \(\mathrm{K}_{2} \mathrm{CO}_{3}(\mathrm{aq})+\mathrm{HClO}_{4}(\mathrm{aq}) \longrightarrow \mathrm{KClO}_{4}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{FeCl}_{2}(\mathrm{aq})+\left(\mathrm{NH}_{4}\right)_{2} \mathrm{S}(\mathrm{aq}) \longrightarrow \mathrm{FeS}+\mathrm{NH}_{4} \mathrm{Cl}\) (c) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+\mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq}) \longrightarrow \mathrm{FeCO}_{3}+\mathrm{NaNO}_{3}\)
See all solutions

Recommended explanations on Chemistry Textbooks

Chemical Analysis

Read Explanation

Making Measurements

Read Explanation

Ionic and Molecular Compounds

Read Explanation

Chemistry Branches

Read Explanation

Physical Chemistry

Read Explanation

The Earths Atmosphere

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.