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JoVE Lab Manual
Lab: Chemistry

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Education
Redox Reactions
 

Learning Objectives

At the end of this lab, students should know...

What is a redox reaction?

A Reduction-Oxidation reaction, or redox reaction, results in a change of the oxidation state of the atoms in the reactants.

What is the oxidation state of an atom?

The oxidation state, or oxidation number, is the charge that an atom would have if each of its bonds to other elements were purely ionic.

How can you identify a redox reaction?

Redox reactions are identified by tracking the oxidation number of each element in the reactants throughout the reaction. If there is no change in oxidation number of the same element in the products, the reaction is not a redox reaction.

What are the four types of simple redox reactions?

The four mechanisms for redox reactions discussed here are the single-displacement reaction, the combustion reaction, the synthesis reaction, and the decomposition reaction.

What is the relationship of the overall charge of a molecule to the oxidation states of its atoms?

The oxidation states of the atoms in a molecule must add up to the total charge of the molecule. For example, the oxidation numbers of the atoms in a neutral molecule must add up to zero.

List of Materials

  • 500-mL filter flask
    5
  • 10-mL graduated cylinder
    15
  • 50-mL graduated cylinder
    5
  • 50-mL beaker
    5
  • 400-mL beaker
    5
  • 83-mm Büchner funnel with rubber adapter
    5
  • Silicone vacuum tubing
    5
  • Rubber stopper (size 15)
    5
  • Glass thermometer
    5
  • Filter paper
    5 boxes
  • pH paper
    5 rolls
  • Hotplate
    5
  • Glass stirring rod
    5
  • Rubber policeman
    5
  • Metal spatula
    5
  • Watch glass
    5
  • Weighing boats
    25
  • Disposable pipettes
    10
  • Deionized water in squeeze bottles
    5
  • Analytical balance (at least 1)
    Dependent on lab size
  • 15.7 M Nitric acid
    50 mL
  • Sodium hydroxide pellets
    25 g
  • 12.1 M Hydrochloric acid
    50 mL
  • 17.8 M Sulfuric acid
    50 mL
  • Copper shot
    5 g
  • Granulated zinc
    10 g
  • Methanol
    100 mL
  • Citric acid
    500 mL
  • Baking soda
    100 g
  • Indicating dessicant
    50 g
  • 100-mL beaker
    3
  • 250-mL beaker
    1
  • 25-mL graduated cylinder
    2
  • 50-mL graduated cylinder
    2
  • 100-mL graduated cylinder
    1
  • 50-mL volumetric flask
    3
  • 250-mL Erlenmeyer flask
    1
  • 150-mL glass bottle
    1
  • 125-mL polyethylene bottle
    3
  • 250-mL polyethylene bottle
    1
  • Glass funnel
    4
  • Small stir bar
    3
  • Medium stir bar
    1

Lab Prep

Source: Smaa Koraym at Johns Hopkins University, MD, USA

  1. Preparation of Solutions

    Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

    • To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves. All solutions for this lab must be prepared inside the chemical hood.
    • First, prepare 50 mL of an 8 M solution of nitric acid. Carefully pour approximately 30 mL of the stock 15.7 M nitric acid into a 100-mL beaker.
      Note: This will make it easier to pour the concentrated nitric acid into the graduated cylinder without spilling.
    • Measure 25.5 mL of stock nitric acid using a 50-mL graduated cylinder and transfer it into a 50-mL volumetric flask. Fill the remainder of the volumetric flask with deionized water until it reaches the appropriately marked line.
    • Place a small stir bar in the flask and set the flask on a stir plate. Mix the solution until it appears homogeneous.
    • Label a 150-mL glass bottle with the solution name and concentration. Transfer the nitric acid solution from the volumetric flask to the bottle using a powder funnel.
    • Prepare 150 mL of 3 M NaOH solution. Weigh 18 g of NaOH pellets using a top-loading balance and transfer the NaOH to a 250-mL Erlenmeyer flask.
    • Measure 150 mL of deionized water into the Erlenmeyer flask. Add a magnetic stir bar to the flask and set it on a stir plate.
    • Mix the solution until the pellets dissolve and the solution appears homogeneous. Then, turn off the stir plate.
    • Label a 250-mL polyethylene bottle '3 M NaOH' and carefully pour the solution into the bottle. Cap the bottle and store it appropriately.
    • Prepare 50 mL of 6.05 M hydrochloric acid solution. First, pour ~30 mL of stock 12.1 M hydrochloric acid into a 100-mL beaker. Then, use a 25-mL graduated cylinder to carefully measure 25 mL of the stock hydrochloric acid. Transfer the hydrochloric acid to a 50-mL volumetric flask.
    • Fill the remainder of the volumetric flask with deionized water until it reaches the marked line on the neck of the flask. Place a stir bar in the flask and set the flask on the stir plate.
    • Stir the solution until it appears homogeneous. Then, transfer the solution to the labeled polyethylene bottle, cap it and store until needed.
    • Finally, prepare 50 mL of 5.93 M sulfuric acid solution. Carefully pour ~20 mL of glacial sulfuric acid into a 100-mL beaker. Then, measure 16.5 mL of the sulfuric acid using a 25-mL graduated cylinder and carefully transfer the sulfuric acid to a 50-mL volumetric flask.
    • Fill the remainder of the flask with deionized water until it reaches the full line on the neck of the flask. Place a magnetic stir bar in the flask, set it on the stir plate, and stir the solution until it appears homogeneous.
    • Label a 125-mL polyethylene bottle with the solution name and concentration, and carefully transfer the sulfuric acid from the volumetric flask to the bottle. Cap the bottle and store it for later.
  2. Preparation of the Laboratory
    • Weigh ~5 g of copper shot into a labeled bottle. Place it by the balance with an empty beaker labeled 'excess', additional weighing tins, and spatulas.
    • Obtain granulated zinc and weigh 7 g into a labeled bottle. Place another empty beaker labeled 'excess', weighing tins, and the bottle of zinc by the balance.
    • Set out one bottle containing methanol and several other bottles containing deionized water.
    • Set out the following glassware and equipment at each workstation (we suggest that students work in pairs):
       1    Disposable 1-mL pipette
       1    500-mL filter flask
       1    83-mm Büchner funnel and adapter
       1    Silicone vacuum tubing
       1    Rubber stopper (size 15)
       1    Glass thermometer
       1    Filter paper
       1    pH paper
       1    Hotplate
       1    Glass stirring rod
       1    10-mL graduated cylinder
       1    50-mL graduated cylinder
       1    50-mL beaker
       1    400-mL beaker

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