Liquid Chemicals: Halogens - Online Tutor, Practice Problems & Exam Prep

Halogens, particularly chlorine and iodine, are effective liquid chemicals for controlling microbial growth. Chlorine disinfects inanimate objects at low concentrations, with forms like sodium hypochlorite (liquid bleach) and chlorine dioxide used for water treatment. Iodine, available as tinctures or iotafor, kills most microbes and is less irritating at low concentrations, making it suitable for antiseptic use. Proper management of these halogens is crucial to avoid toxicity and carcinogenic byproducts, ensuring safe disinfection practices in various settings.

Liquid Chemicals: Halogens

In this video, we're going to begin our lesson on the use of halogens as liquid chemicals for controlling microbial growth. Halogens are highly reactive oxidizing agents, meaning that they are capable of causing other molecules to become oxidized or lose electrons. These halogens can cause damage to proteins and other cell components as well. The halogens, chlorine and iodine, are the most commonly used halogens that are used as disinfectants to control microbial growth. Moving forward in our course, we're first going to talk about chlorine, and then later in our course, we'll talk about iodine. I'll see you all in our next video.

Chlorine

In this video, we're going to talk about the use of the halogen chlorine as a method to control microbial growth. Chlorine is a halogen chemical that disinfects inanimate or non-living objects when used appropriately. Chlorine is generally used at very low concentrations because it is both toxic and corrosive at high concentrations. In some cases, chlorine can react with organic matter to form carcinogenic products or products that contribute to the development of cancer. Thus, the use of chlorine needs to be managed appropriately and used in the correct form.

Chlorine is readily available in multiple forms, including sodium hypochlorite, which is essentially liquid bleach. This is an inexpensive and readily available form of chlorine that you can buy at a grocery store. There is also chlorine dioxide, whose chemical formula is ClO2. This is a less harmful form of chlorine that is used to disinfect drinking water.

Depending on the type or form of chlorine that you are using and the specific concentration of chlorine, it can be used to disinfect either inanimate objects such as surfaces of items and other such things. But it can also be used to disinfect drinking water, thereby making the drinking water safer to consume.

If we take a look at our image down below, at the use of chlorine as a method of controlling microbial growth, notice on the left-hand side we're showing you sodium hypochlorite, which is just liquid bleach. Its chemical formula is, as you see here, sodium with chlorine bound to an oxygen. This is again liquid bleach. But, once again, other forms of chlorine like ClO2 can be used as well, for different purposes.

Depending on the form and the concentration of chlorine, it can be used to either disinfect drinking water or it can be used to disinfect swimming pools, once again at really low concentrations. And that's why we've got this swimming pool here to help remind you that chlorine can be used to disinfect swimming pools. We've also got this guy drinking some water here because the right type of chlorine can be used by water production facilities to help disinfect the drinking water that we drink.

This here concludes our brief lesson on chlorine as a chemical method to control microbial growth, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.

Chlorine:

• A. Readily reacts with organics to produce potentially carcinogenic trihalomethanes.
• B. Is an effective, inexpensive, disinfectant able to destroy all types of microorganisms.
• C. Is unaffected by the presence of organic material.
• D. Is ineffective when diluted.
• E. A and B.
• F. C and D.

Iodine

In this video, we're going to begin our lesson on the use of the halogen iodine as a liquid chemical for controlling microbial growth. Iodine is a halogen chemical that kills most microbes and is often in the form of either a tincture, which, recall from our previous lesson videos, is a chemical dissolved in an alcohol-based solution, or the iodine could be present in what is known as an iodoform. Typically, the tincture form of iodine is more irritating to the skin. However, the iodoform is different. It is a combination of iodine and an organic molecule from which the iodine is slowly released. This slow release of the iodine allows the iodoform to be less irritating to the skin than the tincture would be. The iodoform itself can actually act as a disinfectant or as an antiseptic because it is not as irritating to the skin. This depends on the specific concentration. The use of iodine can vary depending on the form that it takes, whether it is a tincture or an iodoform, as well as the specific concentration of the iodine in the solution. The iodoform itself is not going to be as irritating, so it is non-irritating, specifically at low concentrations when it is used as an antiseptic to treat wounds or burns on the skin. Notice down below, we're showing you the use of iodine, specifically as an iodoform, and notice that this can be used as an antiseptic to treat wounds, such as this cut here that this person has on their finger. This concludes our lesson on the use of the halogen iodine as a liquid chemical for controlling microbial growth. We'll be able to get some practice applying these concepts as we move forward in our course. I'll see you all in our next video.

Which is true of iodine?

• A. It does not readily kill endospores.
• B. It may be used as an antiseptic or as a disinfectant.
• C. It is important to use it at the recommended dilution.
• D. It is usually found as tinctures or iodophors.
• E. All are true.

An iodophor is:

• A. A highly concentrated form of iodine in a water-alcohol solution.
• B. A 2% diluted form of iodine in a water-alcohol solution.
• C. A undiluted form of iodine.
• D. A solid form of iodine.

Here’s what students ask on this topic:

What are the most commonly used halogens for controlling microbial growth?

The most commonly used halogens for controlling microbial growth are chlorine and iodine. Chlorine is often used in various forms such as sodium hypochlorite (liquid bleach) and chlorine dioxide, which are effective for disinfecting inanimate objects and treating drinking water. Iodine is available in forms like tinctures and iotafors, which are used as antiseptics and disinfectants. Both halogens are highly reactive oxidizing agents that can damage proteins and other cell components, making them effective in controlling microbial growth. Proper management of these halogens is crucial to avoid toxicity and carcinogenic byproducts.

How does chlorine disinfect drinking water?

Chlorine disinfects drinking water by reacting with and destroying the cell walls of bacteria and other microorganisms, effectively killing them. It is commonly used in the form of chlorine dioxide (ClO₂), which is less harmful and more effective at low concentrations. Chlorine can also be used as sodium hypochlorite (liquid bleach) in water treatment. The appropriate concentration of chlorine ensures that it is effective in disinfecting the water while minimizing the risk of toxicity and the formation of carcinogenic byproducts. This process makes the drinking water safer for consumption.

What are the differences between tincture and iotafor forms of iodine?

Tincture and iotafor are two forms of iodine used for controlling microbial growth. A tincture is a solution where iodine is dissolved in an alcohol-based solution, which can be more irritating to the skin. On the other hand, an iotafor is a combination of iodine and an organic molecule that slowly releases iodine, making it less irritating to the skin. Iotafors can act as disinfectants or antiseptics, especially at low concentrations, and are suitable for treating wounds or burns. The choice between tincture and iotafor depends on the specific application and desired concentration.

Why is it important to use chlorine at low concentrations?

It is important to use chlorine at low concentrations because, at high concentrations, chlorine is both toxic and corrosive. High levels of chlorine can cause damage to surfaces and pose health risks to humans, including respiratory issues and skin irritation. Additionally, chlorine can react with organic matter to form carcinogenic byproducts, which can contribute to the development of cancer. By using chlorine at low concentrations, it effectively disinfects without causing harmful side effects, ensuring safe and effective microbial control in various applications such as water treatment and surface disinfection.

How does iodine act as an antiseptic?

Iodine acts as an antiseptic by killing most microbes through its strong oxidizing properties, which disrupt the structure and function of microbial cell components. It is commonly used in the form of iotafors, which are less irritating to the skin due to the slow release of iodine from an organic molecule. This makes iotafors suitable for treating wounds and burns. The effectiveness of iodine as an antiseptic depends on its concentration and form, with lower concentrations being less irritating and still effective in preventing infections and promoting healing.