Call Now to Set Up Tutoring:

(888) 888-0446

College Chemistry : Balancing Redox Reactions

Study concepts, example questions & explanations for College Chemistry

Create An Account

All College Chemistry Resources

1 Diagnostic Test 100 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #11 : Reactions

Balance the following redox reaction in acidic conditions:

$\textrm{SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + MnO}_{4}^{-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + Mn}^{2+}(aq)$

Possible Answers:

$\textrm{SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + MnO}_{4}^{-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + Mn}^{2+}(aq)$

$\textrm{2 Mn}^{2+}(aq)\textrm{ + 5 SO}_{4}\textrm{ }^{2-}\textrm{ + 3 H}_{2}\textrm{O}(l)\rightarrow5\textrm{ SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + 2 MnO}_{4}\textrm{ }^{-}(aq)\textrm{ + 6 H}^{+}(aq)$

$\textrm{SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + Mn}^{2+}(aq)\textrm{ + 3 }e^{-}$

$5\textrm{ SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + 2 MnO}_{4}\textrm{ }^{-}(aq)\textrm{ + 6 H}^{+}(aq)\rightarrow\textrm{2 Mn}^{2+}(aq)\textrm{ + 5 SO}_{4}\textrm{ }^{2-}\textrm{ + 3 H}_{2}\textrm{O}(l)$

$\textrm{6 H}^{+}(aq)\textrm{ + SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + Mn}^{2+}(aq)\textrm{ + 3 H}_{2}\textrm{O}(l)$

Correct answer:

Explanation:

Start by writing the half reactions for the equation

$\textrm{SO}_{3}\textrm{ }^{2-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)$

$\textrm{MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{Mn}^{2+}(aq)$

All atoms except for O and H are already balanced, so we can go straight to balancing O and H atoms. First balance O atoms by adding H₂O

$\textrm{H}_{2}\textrm{O}(l)\textrm{ + SO}_{3}\textrm{ }^{2-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)$

$\textrm{MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{Mn}^{2+}(aq)\textrm{ + 4 H}_{2}\textrm{O}(l)$

Now balance H atoms with H⁺

$\textrm{H}_{2}\textrm{O}(l)\textrm{ + SO}_{3}\textrm{ }^{2-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + 2 H}^{+}(aq)$

$\textrm{8 H}^{+}(aq)\textrm{ + MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{Mn}^{2+}(aq)\textrm{ + 4 H}_{2}\textrm{O}(l)$

Balance each half reaction's electrical charge with electrons

$\textrm{H}_{2}\textrm{O}(l)\textrm{ + SO}_{3}\textrm{ }^{2-}(aq)\rightarrow\textrm{SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + 2 H}^{+}(aq)\textrm{ + 2 }e^-$

$\textrm{5 }e^{-}\textrm{ + 8 H}^{+}(aq)\textrm{ + MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{Mn}^{2+}(aq)\textrm{ + 8 H}_{2}\textrm{O}(l)$

Now combine both half reactions to get the overall reaction. Be sure to cancel out electrons by multiplying the oxidation reaction by 5 and the reduction reaction by 2. This will give 10 e^- on each side of the overall reaction so that they cancel out.

$\textrm{5 H}_{2}\textrm{O}(l)\textrm{ + 5 SO}_{3}\textrm{ }^{2-}(aq)\rightarrow\textrm{5 SO}_{4}\textrm{ }^{2-}(aq)\textrm{ + 10 H}^{+}(aq)\textrm{ + 10 }e^-$

$\textrm{10 }e^{-}\textrm{ + 16 H}^{+}(aq)\textrm{ + 2 MnO}_{4}\textrm{ }^{-}(aq)\rightarrow\textrm{2 Mn}^{2+}(aq)\textrm{ + 8 H}_{2}\textrm{O}(l)$

Overall Reaction:

$\textrm{5 H}_{2}\textrm{O}(l)\textrm{ + 16 H}^{+}(aq)\textrm{ + 5 SO}_{3}\textrm{ }^{2-}(aq)\textrm{ + 2 MnO}_{4}\textrm{ }^{-}(aq)\rightarrow$

$\textrm{5 SO}_{4}\textrm{ }^{2-}(aq)\textrm{Mn}^{2+}(aq)\textrm{ + 8 H}_{2}\textrm{O}(l)\textrm{ + 10 H}^{+}(aq)$

Notice that we have H₂O and H⁺ on both sides of the equation, so we need to simplify. Subtract the 5 H₂O on the reactant side from the 8 H₂O on the product side which leaves 3 H₂O on the reactant side. Then subtract the 10 H⁺ on the product side from the 16 H⁺ on the reactant side which leave 6 H⁺ on the reactant side. Now we have the simplified overall reaction

Report an Error

View Tutors

Yucheng
Certified Tutor

The University of Texas at Austin, Bachelor of Science, Mechanical Engineering.

View Tutors

Yuliya
Certified Tutor

University of Maryland-College Park, Bachelor of Science, Mathematics. George Washington University, Masters in Education, Ed...

View Tutors

Cibele
Certified Tutor

Universidade Estadual do Piaui, Bachelor in Arts, Spanish.

All College Chemistry Resources

1 Diagnostic Test 100 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

GMAT Tutors in San Diego, French Tutors in Boston, Computer Science Tutors in Phoenix, GMAT Tutors in Phoenix, Calculus Tutors in San Francisco-Bay Area, English Tutors in Washington DC, Chemistry Tutors in Washington DC, SSAT Tutors in Miami, ACT Tutors in Miami, SSAT Tutors in Los Angeles

Popular Courses & Classes

ACT Courses & Classes in Atlanta, ACT Courses & Classes in Phoenix, ACT Courses & Classes in San Francisco-Bay Area, SSAT Courses & Classes in Miami, GRE Courses & Classes in Dallas Fort Worth, ISEE Courses & Classes in Chicago, SAT Courses & Classes in Phoenix, SSAT Courses & Classes in Philadelphia, MCAT Courses & Classes in San Francisco-Bay Area, SAT Courses & Classes in New York City

Popular Test Prep

ACT Test Prep in San Diego, ISEE Test Prep in New York City, MCAT Test Prep in New York City, SSAT Test Prep in Washington DC, MCAT Test Prep in Chicago, ISEE Test Prep in Atlanta, ACT Test Prep in San Francisco-Bay Area, GMAT Test Prep in Dallas Fort Worth, LSAT Test Prep in Chicago, GMAT Test Prep in Washington DC

DMCA Complaint

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105

Or fill out the form below:

Do not fill in this field

Contact Information

* Full legal name

Company name

* Phone number

* Email address

Address

* Address1

Address2

* City

* State

* Zipcode

* Country

Complaint Details

* URL of copyrighted work (where your original material is located)

* Please describe the copyrighted work so that it may be easily identified

I am the owner, or an agent authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.

I have a good faith belief that the use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law.

This notification is accurate.

I acknowledge that there may be adverse legal consequences for making false or bad faith allegations of copyright infringement by using this process.

* Signature (your digital signature is legally binding)

HIGH SCHOOL

GRADUATE SCHOOL

K-8

Search 50+ Tests

math tutoring

science tutoring

foreign languages

elementary tutoring

other

Search 350+ Subjects

College Chemistry : Balancing Redox Reactions

Study concepts, example questions & explanations for College Chemistry

All College Chemistry Resources

Example Questions

Example Question #11 : Reactions

All College Chemistry Resources

Report an issue with this question

DMCA Complaint

Contact Information

Address

Complaint Details

Email address:
Your name:
Feedback: