I am trying to calculate the mass (after a certain time) of a material that we know is sublimating at , say .000123 g/(cm^2 hr). And when warming, it goes directly from a solid to a gas! Sublimation rate of solids Thread starter tempneff; Start date Sep 25, 2014; Sep 25, 2014 #1 tempneff. Does it really matter what the box size is, if for example I took 4 of our 19lt EPS range with a simulated product load and started with 10 kilos of dry ice would the results be indicitive for any of the box sizes and could the result be scaled up as well as down (for example 1 kilos would last x and maintain the temperature range y for z time or 20 kilos would last x and maintain the temperature range y for z time. Typically the journey times we encounter are 3 hours (domestic) to 72 hours (Extreme transit International) so would the data still be valid if at the end I said box type a, b, c or d for a journey time of 3, 6, 12, 24, hours etc.? Consider the ventilation flow rates in any cargo compart- ment containing dry ice packages. The sublimation rate of ice is commonly calculated using the simple Hertz–Knudsen formula. by steveh » 25 Feb 2012, 05:38, Post Describe the properties of a solid, a liquid, and a gas. graduated cylinder, preferably tempered glass For reasons I’m not at liberty to discuss, we had a cooler of dry ice pellets in the freezer for a few days. Per Demo or Class: styrofoam container or another appropriate container for dry ice (It is very important as there are specific methods of transporting dry ice.) Be very careful when handling dry ice and ensure to wear the proper safety gear and use the correct safety equipment. Need help calculating your dry ice order? dustry.pdf. To dispose of excess dry ice, place it in an empty container and leave it to sublimate in an open, secure and safe area with good ventilation. Teacher tip: Test out the demonstration ahead of time to determine the best ratios and methods of the procedure before the live demonstration. by HansV » 23 Feb 2012, 10:03, Post Dry ice is the solid form of carbon dioxide (CO 2), a molecule consisting of a single carbon atom bonded to two oxygen atoms.Dry ice is colorless, odorless, and non-flammable, and can lower the pH of a solution when dissolved in water, forming carbonic acid (H 2 CO 3).. At pressures below 5.13 atm and temperatures below −56.4 °C (216.8 K; −69.5 °F) (the triple point), CO 2 changes … As a general rule, Dry Ice will sublimate at a rate of five to ten pounds every 24 hours in a typical ice chest. This document sug- gests an area-based rate of 250 g/m2 ? This sublimation continues from the time of purchase; therefore, pick up Dry Ice as close to the time needed as possible. What do you want in the blank cells? The sublimation rate used in AC 103-4 to calculate permissible dry ice loads was based on a study conducted by Pan American Airlines where a single, large piece of dry ice (100 lb block) was used. This sublimation continues from the time of purchase; therefore, pick up Dry Ice as close to the time needed as possible. (goggles, tongs, gloves). However, if one uses … The numbers don't come out too different than using Hans' formula, but being a Chemist, I prefer presuming a 1st order exponential loss and using the equation: I'm not a chemist, so I'm happy to accept your solution as the better one. The key for selling dry ice is a constant supply either from manufacturing as … dry ice forms) in a process called deposition. Teacher tip: A 3:1 ratio of water to dry ice in volume will create a good fog effect. Use the lowest possible coefficients.) I started with “10 pounds” of dry ice in a half-pound Styrofoam container with 1.5-inch thick walls; the total weights include the container. When dry ice is placed into warm water, a cloud forms. Liquid CO2 is not stable at atmospheric pressure, however in a CO2 fire extinguisher; the CO2 is liquid (at about 840 psi). 0000003671 00000 n 0000005131 00000 n Courtesy UC Davis Chemwiki\CC-BY-NC-SA-3.0. Dry ice undergoes the process of deposition or sublimation at the critical temperature of −78°C (-109.3°F). The derivation relies on geometrical considerations, the ideal gas law, and the Maxwell–Boltzmann distribution for the speed of free gas molecules (e.g., Bohren and … insulated gloves for handling dry ice Sublimation is the process by which dry ice, which is frozen CO2, converts over time to gaseous CO2.