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JoVE Lab Manual
Lab: Chemistry

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Education
Temperature Dependence
 

Learning Objectives

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

What is the reaction rate, and what factors affect it?

The reaction rate is a measure of the speed of a chemical reaction, and it is described as the change in concentrations over time. Reaction rate is affected by the concentration of the reactants, the temperature, pressure, and the state of matter of the reactants.

What is a reaction's rate law?

A reaction’s rate law is an experimentally determined relationship between the concentration of the reactants raised to their reaction order times the reaction rate constant, k. The constant k is temperature-dependent.

What is the activation energy of a reaction?

The activation energy of a reaction is the amount of energy required for a chemical reaction to occur. If a chemical reaction does not meet this threshold of energy, it will not take place.

How are the reaction rate constant and activation energy of a reaction related?

The reaction rate constant, k, and activation energy of a chemical reaction are related by the Arrhenius equation. This equation states that the rate constant is dependent on the temperature and activation energy of a chemical reaction.

What is a catalyst?

A catalyst facilitates a chemical reaction by lowering the activation energy required. The catalyst is not consumed by the chemical reaction. Catalysts increase the rate of a reaction but do not affect the yield of the reaction.

List of Materials

  • Lab tape
    5 rolls
  • 125-mL glass Büchner flask
    5
  • 50-mL glass beaker
    5
  • 100-mL glass beaker
    5
  • 400-mL glass beaker
    15
  • 600-mL glass beaker
    5
  • 50-mm watch glass
    10
  • 20-mL volumetric pipette
    5
  • Pipette controller
    5
  • Hotplate
    5
  • Lab stand
    5
  • Medium 3-prong clamp
    5
  • Thermometer clamp
    5
  • Glass thermometer
    5
  • Data acquisition device
    5
  • Flask drive
    5
  • Gas pressure sensor
    5
  • Flexible polymer tubing about 18" long
    5
  • Male Luer-lok
    10
  • Female Luer-lok
    10
  • Two-way locking stopcock
    5
  • 20-mL plastic Luer lock syringe
    5
  • Two-hole rubber stopper (#5)
    5
  • 125-mL plastic wash bottle
    5
  • 3 wt% hydrogen peroxide without added stabilizer
    1 L
  • Fe(NO3)3·9 H2O
    60 g
  • Powder funnel
    1
  • 250-mL glass Erlenmeyer flask
    1
  • 250-mL glass graduated cylinder
    1
  • 250-mL polyethylene bottle with cap
    1
  • Magnetic wand
    1
  • Medium stir bar
    1
  • Stir plate
    1
  • Weighing boats
    1
  • Spatula
    1
  • Top-loading balance
    1
  • Insulated cooler
    1
  • Crushed or chipped ice
    Dependent on lab size
  • Deionized water
    Dependent on lab size

Lab Prep

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

  1. Preparation of 0.5 M Fe(NO3)3

    Here, we show the preparation of a solution 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
    • Prepare 250 mL of a 0.5 M aqueous solution of iron (III) nitrate. Measure out 50.5 g of iron nitrate nonahydrate on a top-loading balance. Place a powder funnel in the mouth of a 250-mL Erlenmeyer flask and pour the iron (III) nitrate nonahydrate into it.
    • Measure out 175 mL of deionized water with a graduated cylinder and pour it into the flask.
    • Remove the funnel, place a stir bar in the flask, and start stirring the mixture on a stir plate. While the mixture stirs, label a 250-mL polyethylene bottle as ‘0.5 M Fe(NO3)3’.
    • Once the solution appears homogeneous, place the funnel back in the flask and add another 75 mL of deionized water.
    • Continue stirring until the solution appears homogeneous again. Then, turn off the stir motor and remove the stir bar from the flask.
    • Transfer the solution into the polyethylene bottle. Store the capped bottle at the back of the instructor's hood until just before the lab.
    • Lastly, wash your glassware and equipment and put away the iron (III) nitrate nonahydrate.
  2. Preparation of the Laboratory
    • Place a labeled waste container for aqueous iron solutions in the back of the hood.
    • Make sure each workstation is equipped with a hotplate and a support rod, a medium 3-prong clamp, and a thermometer clamp. Attach both clamps to the support rod, and confirm that the vacuum sources are equipped with silicone tubing.
    • Ensure that each sink has plenty of paper towels.
    • Assemble the gas pressure sensor devices. Confirm that the devices are charged and working before distributing them to the workstations.
    • Make sure two locking tapered stopper adapters are tightly attached to the flexible polymer tubing and set one at each workstation along with a 20-mL Luer-Lok syringe, a two-way locking stopcock, and a number five 2-hole rubber stopper.
    • Set out the following equipment and glassware at each lab station (we suggest that students work in pairs):
       1    20-mL volumetric pipette
       1    Pipette controller
       1    50-mL beaker
       1    100-mL beaker
       3    400-mL beakers
       1    600-mL beaker
       1    125-mL Büchner flask
       1    Roll of lab tape
       1    Labeling pen
       1    Glass thermometer
    • Fill a 125-mL wash bottle with deionized water, and set one at each workstation.
    • Shortly before the lab, fill an insulated cooler or bucket with crushed or chipped ice. Place the cooler in a central area.
    • Finally, place a 1-L bottle of 3 wt% hydrogen peroxide in the central hood.

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