Jove Lab Chem
Stoichiometry, Product Yield, and Limiting Reactants — Lab Prep
Source: Smaa Koraym at Johns Hopkins University, MD, USA
- Preparation of 25% v/v Ethylenediamine in Deionized Water
Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.
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To set up for this lab experiment, wear the appropriate personal protective equipment, including a lab coat, chemical splash goggles, and gloves. Note: Ethylenediamine is toxic, caustic, flammable, and corrosive. This solution must be prepared and used in a fume hood.
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Prepare 200 mL of a 25% v/v solution of ethylenediamine in deionized water. Pour about 50 mL into a 250-mL beaker.
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Place a powder funnel in a 50-mL graduated cylinder and measure 50 mL of ethylenediamine.
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Transfer the ethylenediamine to a 200-mL volumetric flask. Add deionized water to the flask until the solution level reaches the line.
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Add a magnetic stir bar to the flask, then place it on a stir plate, and mix the solution for approximately one to two minutes until it is homogeneous. Turn off the stir plate when finished.
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Label a brown glass dispensing bottle ‘25% v/v ethylenediamine’. Remove the dispensing pump and use a funnel to transfer the ethylenediamine solution to the bottle.
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Reconnect the glass dispensing pump with a 20 mL capacity to the bottle.
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Retrieve the stir bar with a magnetic wand and set both on a paper towel to absorb the excess liquid. Store the bottle in a flammables cabinet until it is needed.
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When finished, thoroughly clean the volumetric flask, graduated cylinder, funnel, and stir bar, using your lab standard practices. Store the ethylenediamine in its approved storage location.
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- Preparation of the Laboratory
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Fill out labels for organic, aqueous, and solid nickel waste containers according to the waste disposal procedures of your institution. Place the labeled containers in an approved waste collection area.
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Ensure that the following glassware and equipment are available at each workstation (we suggest that students work in pairs):
2 10-mL graduated cylinders 1 100-mL beaker 1 400-mL beaker 1 600-mL beaker 1 800-mL beaker 1 500-mL filter flask 1 Glass stirring rod 1 Büchner funnel (40-mL/83-mm) 1 Filter adapter (size 4) 1 Neoprene stopper (size 15) 1 Rubber policeman 1 Roll of lab tape with pen/marker Silicone tubing -
Set out packages of circular filter paper and disposable 1-mL plastic pipettes so that each workstation has access to them.
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Place at least 3 L of ice in an insulated cooler with a scoop and set out paper towels as needed.
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Obtain a container of nickel chloride hexahydrate and set it by the analytical balances. Verify that the balances have a sufficient supply of weighing boats, clean spatulas, and laboratory wipes.
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Fill five 100-mL polyethylene bottles with acetone. Place a squeeze bottle of deionized water and a bottle of acetone at each workstation.
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Label five tall-form beakers with ‘25% v/v ethylenediamine’. Bring the labeled beakers and five watch glasses to the hood with the ethylenediamine solution.
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When a student group is ready, use the glass pump to dispense 20 mL of ethylenediamine into a labeled beaker. Cover the beaker and carefully hand it to the students.
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