Pressure


Buldging Drums

Thes can be a real problem as you know on a response. Sometimes the vapors just expand enough when its real hot out and can push the steel to buldge the top of a container. Other times it could be that chemcials were mixed and the products have increased the pressure of the drum. To lead into this conversation we have a simple demo for you!

Concepts:

Chemical reactions, vapor pressure, temperature changes vapor pressure

Safety:

  • Safety glasses MUST be worn at all times by demonstrator and the audience.

  • The canister can pop up very quickly do not lean over the tray.

  • Ensure there are no overhead sprinklers

Equipment:

Preparation:

  1. Line up the film canister with the lids behind the canister.

  2. Fill the canister with water up to about 50%.

  3. Place a half piece of Alka-Seltzer behind the lid. Smaller piece will take longer. Use different sizes.

  4. You can time the reaction for the size of the Alka-Seltzer.

  5. You can vary the water temperature for faster results use warm water.

Demonstration Instructions

  • When you are ready place each tablet in the canister one by one. Snap the lid on tightly and move onto the next one. Depending on the volume of water, temperature and size of Alka-Seltzer they may pop within 15-20 seconds.

  • The canister can be left up right and just the lids will fly off and most of the water will remain in the canister. If inverted the whole canister will go up causing a bit more of a mess.

  • Start at 1:30 min. https://www.youtube.com/watch?v=WMClPxoZyko

Observations:

The class will see the instant reaction between the liquiid and solid creating gas bubbles and pressure. Eventually the lids will fly off due to the pressure created by the chemical reaction. Sometimes not all lids will pop off but a fair ammount of pressure remains inside the canister.

Learning Outcomes:

There is a lot of topics to cover here. It can go in many different ways depending on what you want to cover.

  1. Chemical reactants = chemical products.

    • Gases could be Flammable, Non-Flammable or Toxic.

    • Alka-Seltzer contains Citric Acid and Sodium Bicarbonate (Baking Soda). This produces Carbon Dioxide gas.

    • But you can take this topic into chemical suicides that use pesticides mixed with acids or hydrides with water or cyanide salts with acid.

  2. The products are what will need to be monitored so this also leads into monitor selection.

  3. Using Chemical Companion, Wiser or Cameo Chemicals to figure out what the products will be.

  4. Vapor pressure.

  5. Safety! Mitigation tactics.

  6. Temperature with volatile solvents.

  7. Thermal Imaging Cameras (TIC).

  8. Hazardous waste containers with incompatiable waste.

Chemical Disposal:

its just Alka-Sletzer and water. You can dispose of in the sink.

Additional Information:

  • You can alwalys scale this up by gluing the canister to a board (Lid on, glue on lid, place on board).

  • Then you can line up all the canister on a table

  • Glue the Alka-Seltzer piece to the lid

  • Fill the canisters with water

  • Put the lid on

  • Flip the board and the canister portion will fly up in the air. Kinda messy.

  • If doing this with kids you can make rockets out of these

  • https://www.youtube.com/watch?v=PVDWq5CeE-g