Chemical Gases: Ethylene Oxide, Ozone, & Formaldehyde
11. Controlling Microbial Growth
Chemical Gases: Ethylene Oxide, Ozone, & Formaldehyde - Video Tutorials & Practice Problems
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1
concept
Chemical Gases: Ethylene Oxide
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in this video, we're going to begin our lesson on chemical gases for controlling microbial growth, specifically ethylene oxide, ozone and formaldehyde. Now in this video we're only going to focus on ethylene oxide. But moving forward and our next lesson videos, we'll talk about ozone and formaldehyde. And so ethylene oxide is a highly flammable and potentially explosive gas sterilizer, meaning that it's capable of killing all microbes, including endo spores, which are really resistant. Now. Although ethylene oxide is a gas sterilizer capable of killing all microbes, it does require really long treatment times. And so that is a slight disadvantage. Also, another disadvantage of ethylene oxide is that it is potentially carcinogenic, meaning that it is capable of contributing to the development of cancer and therefore because it is highly flammable, potentially explosive and carcinogenic, it must be removed from the sterilized material. After treatment with ethylene oxide and the ethylene oxide is removed by forcing out the ethylene oxide with air. Now, sterilization via ethylene oxide treatment must be carried out in a specialist chamber in order to control variables such as temperature, humidity and the concentration at which the ethylene oxide gas is used. And all of these variables are variables that are important and can affect the use of ethylene oxide. And so notice down below, we're showing you an image of ethylene oxide over here. On the left hand side, we're showing you the chemical structure of ethylene oxide. And once again, this is a very dangerous, highly flammable, potentially carcinogenic and explosive gas. And so it must be carried out in a specialized chamber as you see here. And so this is the ethylene oxide treatment chamber. And so one of the good uses of ethylene oxide is because it is a gas, it is highly penetrative, which means that it can penetrate into things um that might be difficult to reach otherwise. And so it can get into mattresses, for example, or pillows, basically areas that might otherwise be difficult to reach because ethylene oxide is a gas, it can reach these areas that are difficult to reach. And it's also good for treating uh materials that are heat sensitive and moisture sensitive, such as electrical equipment. And so ethylene oxide is a, a method that is used to control microbial growth in some scenarios. And so this year concludes our brief lesson on ethylene oxide as a chemical gas for controlling microbial growth. And once again, as we move forward in our course, will be able to apply these concepts and we'll also get to talk about ozone and formaldehyde gases. And so I'll see you all in our next video.
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Problem
Problem
Ethylene oxide is gas that:
A
Requires special conditions when being used.
B
Is potentially carcinogenic.
C
Is used as a 37% aqueous solution.
D
Is effective against all microorganisms except endospores and viruses.
E
A and B.
F
C and D.
3
concept
Formaldehyde Gas
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2m
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in this video, we're going to talk about yet another chemical gas used for controlling microbial growth. And that is formaldehyde gas. And so formaldehyde gas is a colorless, strong smelling Aldo hide in a gas form that is made by oxidizing a chemical called methanol whose chemical formula is C. H. 20 Now, formaldehyde gas can actually be used as a disinfectant at a 3% dilution, or it could be used as a sterile lint at a higher concentrated form of a 37% solution. And although formaldehyde is available in a gas form, It's also commonly available in a 37% acquis solution or a liquid form that is called formal in And so formula is really just the liquid version of formaldehyde. Now whether you're using formaldehyde gas or this liquid form of formaldehyde formula, it is going to kill microbes by causing protein D. N. A. Cross linking basically co valiantly linking proteins to DNA. And this cross linking will eventually damage the D. N. A. And denature proteins and of course damaging the DNA. And DNA featuring proteins can lead to the destruction of the microbe, allowing formaldehyde gas and formula to be used to control microbial growth. So if we take a look at this image down below, we're focusing in on formaldehyde as a gas. And over here we're showing you the chemical formula, the chemical structure of formaldehyde. And over here what we have is a little bottle that can contain the liquid version of formaldehyde, the formal in equally a solution. And so the use of formaldehyde gas or this liquid formula in form of formaldehyde will lead to the same result. And so the formaldehyde is able to diffuse across a cells plasma membrane here and it's able to interact with proteins that are found inside the cell and it's also able to interact with the D. N. A. That's found inside the cell as well. And so it can cause these DNA protein cross links basically co violently linking the protein to the D. N. A. And that can again damage the D. N. A. And denature proteins leading to the destruction of the microbe. And so this year concludes our brief lesson on the use of formaldehyde gas as a means for controlling microbial growth. And we'll be able to get some practice applying these concepts and then learn about ozone in our next lesson video. So I'll see you all in that video.
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Problem
Problem
___________ is the commercially available form of formaldehyde in a 37% aqueous solution.
A
Aldehyde.
B
Formalin.
C
Methanol.
D
Hydrogen Peroxide.
5
concept
Ozone
Video duration:
1m
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in this video, we're going to briefly discuss yet another type of chemical gas used for controlling microbial growth. And that is ozone. And so ozone actually has a chemical formula of 03 minus. And so if we take a look at our image down below, notice that on the left hand side over here we're showing you the chemical structure of ozone. Now, ozone is actually a very unstable form of oxygen, and ozone can actually serve as a strong oxidizing agent, which means that ozone can cause other molecules around it to become oxidized or to lose electrons. Now because ozone is so unstable, ozone is also going to be very highly reactive. And so ozone can react to form free radicals which are also very reactive molecules and are also very dangerous to cells because free radicals can actually lead to sell license or sell rupturing, causing the cell to die. And so this is how ozone can be used as a method of controlling microbial growth. Because ozone can lead to cell license now again because ozone is so unstable and so highly reactive ozone is actually going to decompose very, very quickly. And because it decomposes so quickly, it means that ozone must be generated on site with a generator in order for scientists to use the ozone as a method of controlling microbial growth. And so notice that down below in our image on the right hand side, we're showing you an ozone generator and ozone is often used as an alternative to chlorine or disinfecting water disinfecting drinking water. And so ozone is going to be a very important method of controlling microbial growth in some certain circumstances. And so if we take a look at our image down below, notice that again in the middle, we're actually showing you an uh an image of our atmosphere because ozone plays a role uh in the atmosphere to help protect us from UV light that comes from the sun or ultraviolet light that comes from the sun. But this year concludes our brief lesson on ozone and it's used as a method of controlling microbial growth and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.
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Problem
Problem
Which of the following statements about ozone is FALSE?
A
It can be used to disinfect drinking water.
B
It is a strong oxidizing agent.
C
It causes cell lysis when free radicals form in water.
