Dry Ice Composition and Uses

Dry Ice Composition and Uses Dry ice is the general term for solid carbon dioxide (CO), coined in 1925 by Long Island-based Prest Air Devices. Though originally a trademarked term, dry ice has become the most common way of referring to carbon dioxide in its solid, or frozen, state. How Is Dry Ice Manufactured? Carbon dioxide is frozen by compressing carbon dioxide gas to a high pressure to create dry ice. When it is released, as liquid carbon dioxide, it quickly expands and evaporates, cooling some of the carbon dioxide down to the freezing point (-109.3 F or -78.5 C) so that it becomes solid snow. This solid can be compressed together into blocks, pellets, and other forms. Such dry ice snow also forms on the nozzle of a carbon dioxide fire extinguisher when it is used. Special Properties of Dry Ice Under normal atmospheric pressure, dry ice undergoes the process of sublimation, transitioning directly from solid to gaseous form. In general, at room temperature and normal pressure, it sublimates at a rate of 5 to 10 pounds every 24 hours. Because of the very low temperature of dry ice, it is used for refrigeration. Packing frozen food in dry ice allows it to remain frozen without the mess that would be involved with other cooling methods, such as water from melted ice. Several Uses of Dry Ice Cooling materials- food, biological samples, perishable items, computer components, etc.Dry ice fog (see below)Cloud seeding to increase precipitation from existing clouds or decreasing cloud thicknessTiny pellets can be shot at surfaces to clean them, similar to sanding ... since it sublimates, the benefit is less residue to clean upVarious other industrial uses Dry Ice Fog One of the most popular uses of dry ice is in special effects, to create fog and smoke. When combined with water, it sublimates into a cold mixture of carbon dioxide and humid air, which causes condensation of water vapor in the air, forming fog. Warm water speeds up the process of sublimation, producing more dramatic fog effects. Such devices can be used to make a smoke machine, although simplified versions of this could be created by putting dry ice in water and using fans on low settings. Safety Instructions Do not taste, eat or swallow! Dry ice is very cold and can damage your body.Wear heavy, insulated gloves. Since dry ice is cold, it can damage even your skin, giving you frostbite.Do not store in sealed container. Because dry ice constantly sublimates into carbon dioxide gas, storing it in a sealed container will cause pressure to build up. If it builds up enough, the container could explode.Use only in ventilated space. In a poorly ventilated area, the build up of carbon dioxide could create a suffocation hazard. This is a great danger when transporting the dry ice in a vehicle.Carbon dioxide is heavier than air. It will sink to the floor. Keep this in mind when thinking about how to make the space ventilated. Obtaining Dry Ice You can buy dry ice at most grocery stores. You have to ask for it, though. Sometimes there might be an age requirement on buying dry ice, requiring someone age 18 or over. Edited by Anne Marie Helmenstine, Ph.D.

Sentence Flow

Sentence Flow Sentence Flow Sentence Flow By Maeve Maddox David writes: I was wondering if you could share your thoughts on how to flow from sentence to sentence. I feel mine can be a bit jumpy as I tell the story. Much is written about â€Å"transition sentences,† that is, sentences that bridge paragraphs, but that’s not what this question is about. This question is about what a writer can do to avoid writing paragraphs that all progress to a beat of dumpty-dumpty-dump. Two things contribute to the flow of sentences within a paragraph: 1. sentence length 2. logical progression of thought In browsing my shelves for examples, I realized that some very popular writers don’t seem to share David’s concern regarding â€Å"jumpy† narration. Here’s a typical paragraph from Dan Brown’s The Da Vinci Code: Langdon and Sophie stepped into another world. The small room before them looked like a lavish sitting room at a fine hotel. Gone were the metal and rivets, replaced with oriental carpets, dark oak furniture, and cushioned chairs. On the broad desk in the middle of the room, two crystal glasses sat beside an opened bottle of Perrier, its bubbles still fizzing. A pewter pot of coffee steamed beside it. Not a complex sentence in sight. It doesn’t seem to matter if Brown is being reflective or describing action. Most of his sentences are simple or compound. Here and there the reader comes across a noun clause introduced by that, or a an adverb clause introduced by as or as if. Mostly it’s dumpty-dumpty-dump. Yes, Dan Brown is a wildly successful writer and I’m happy for him. His gift, however, is story-telling, not writing style. Here are two examples from a novel by a writer who is both an effective story-teller and a fine stylist. The first is a paragraph in which the narrator is reflecting on his life. He is attending the opera with his employer. I suppose I had once aspired to come here and walk among these beautiful, elegant people as one of their own, but that had been long ago, before all my dreams had been dashed like porcelain on paving stones. Now that I was finally here, I felt all the more like a Welsh collier’s brat, as if I were still twelve, nose running, and starting to outgrow my brother’s cast-offs. I was in the right place at the wrong time. Such was the refrain of my life. Some Danger Involved by Will Thomas The first sentence is long and leisurely, suggesting reflection. It contains no fewer than four clauses and numerous phrases. The second sentence has multiple clauses and phrases, but the last two are simple sentences, brusquely bringing the introspection back to the present moment. The second example is from an action paragraph in which the narrator is about to be murdered. The cross spun in a circle, and when it stopped, a pistol was clapped to my head. It was my own revolver. I recognized the filed-down sight. I closed my eyes and felt surprisingly at ease. I was ready to die now. I gave it all over. At that point, I would have preferred a bullet to slow death. Ibid. The first sentence has three clauses joined by the most commonplace conjunctions and and when. The loosely joined clauses suggest a spinning motion. The next two sentences are simple and staccato. Short sentences take the reader along rapidly. They convey the breathlessness felt by the man in danger. The next sentence has two clauses, but they are short and, again, joined by the nearly invisible and. The next three sentences are simple. With the length of the sentences the writer has conveyed both the fear and resignation felt by the narrator. The writer striving for a pleasantly flowing style will vary sentence length and kind, crafting length to thought. Here are some joining words with which to introduce subordinate clauses. Subordinate conjunctions after, although, as, as if, as long as, as much as, as soon as, as though, because, before, even if, even though, how, if, inasmuch, in order that, lest, now, provided (that),   since, so that, than, that, though, till, unless, until, when, whenever, where, wherever, while, Conjunctive adverbs accordingly, also, anyway, again, besides, certainly, consequently, contrarily, finally, further, furthermore, elsewhere, hence, henceforth, however, in contrast, incidentally, indeed, instead, likewise, meanwhile, moreover, namely, nevertheless, next, nonetheless, now, otherwise, rather, similarly, so, subsequently, still, that is, then, thereafter, therefore, thus, undoubtedly, yet Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Fiction Writing category, check our popular posts, or choose a related post below:Good At, Good In, and Good With20 Words Meaning "Being or Existing in the Past"Epidemic vs. Pandemic vs. Endemic