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Katarzyna Roberts Chemistry 2 26 January 2019 Colloids An example of a colloid is glue, the word Colloid even means “like glue” coming from the Greek words kolla, meaning “glue,” and eidos, meaning “like.” They are a suspension of larger particles, but they are too small for gravity to settle them. Colloids can be the result of any combination of physical states that you can imagine. In colloids, you have the dispersed phase, which is whatever you have that is a smaller amount in comparison to the dispersed medium like when comparing the solute of a solution to the solvent. The dispersed phase is the component within the dispersed medium, likewise, the solute is the component within the solvent in a solution. The three different types of mixtures include colloids, solutions, and suspensions. Colloids are very different from solutions and suspensions. Solutions are homogeneous mixtures, meaning that they have a uniform composition, of two or more pure substances, such as salt and water. In solutions, the particles are much smaller than any other mixture. In fact, true solutions have the smallest particles in comparison to colloids and suspensions. To distinguish whether a mixture is a colloid or suspension, you have to find out if the particles settle or not. Unlike solutions, suspensions are heterogeneous mixtures, meaning that it does not have a uniform composition, containing large solid particles that settle. If they do not settle, it is a colloid. An example of a suspension would be sand and water. Colloids and suspensions both have large particles, but in general, the particles in suspensions are larger than those in colloids.

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A solid, the dispersed phase, in a gas, the dispersed medium, creates smoke which is an aerosol colloid. The physical state of smoke is gas. According to “Generation and Transport of Smoke Components” by Kathryn M. Butler and George W. Mulholland at the National Institute of Standards and Technology, “smoke is a mixture of gases, vapors, and suspended particulate matter, or aerosols.” When something is burning, acetylene, benzene, and small hydrocarbons form. The three react together to form polycyclic aromatic hydrocarbons that grow and grow via coagulation into soot creating the suspended particulate matter. Vaporized PAHs form on soot as the smoke from a fire cools off. This soot absorbs gases such as water and benzene vapor. A gas, the dispersed phase, in a gas, the dispersed medium, creates fog which is an aerosol colloid. The physical state of fog is gas. You might start freaking out if you are at a concert and you aren’t sure if it’s fog or some type of vaporized drug coming out of the fog machines. Not to worry, it more than likely is fog because the people operating the lights want to make a laser show. If you try to shine a light on air, no one will be able to see the cool tricks you’re doing with lasers. That’s why fog is such a great colloid. Colloidal suspensions, such as fog, scatter rays of light, allowing Roger Waters fans to see a gigantic Dark Side of the Moon prism in the form of lasers at the BOK Center. Called the Tyndall Effect, which can cause colloidal mixtures to appear cloudy or even opaque. It is also the same reason why you aren’t supposed to use your bright lights while driving in the fog because the light will scatter, making using your bright lights pointless. A solid, the dispersed phase, in a liquid, the dispersed medium, creates ink or paint and called sol. The physical state of this is liquid. A solid used in paint before 1978 was lead. It is a serious problem for babies, especially. Everyone knows that they love to chew on anything and everything, even painted toys. It is such a problem that major home stores sell Lead in Paint test

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kits. Lead poisoning can cause a loss of developmental skills. The United States Environmental Protection Agency issued a Federal Action Plan to Reduce Childhood Lead Exposure in December of 2018 with goals to “reduce children’s exposure to lead sources…identify leadexposed children and improve their health outcomes…communicate more effectively with stakeholders…support and conduct critical research to inform efforts to reduce lead exposures and related health risks” (EPA). If President Trump has done anything good in his administration, this plan was it. A solid, the dispersed phase, in a solid, the dispersed medium, creates a solid sol colloid. The physical state of this is solid. Stained-glass, used for the windows in churches, is an example of a solid sol colloid. These windows create colorful artwork that usually tells of biblical stories. The Augsburg Cathedral, founded in the 11th century, still stands today with the oldest surviving stained-glass windows. It is a Roman Catholic Church in Augsburg, Bavaria, Germany and is one of the city’s main attractions. Due to the Tyndall Effect, glass scatters light. A liquid, the dispersed phase, in a gas, the dispersed medium, creates aerosols like clouds and the stuff you spray in your house to make it smell good. The physical state of this is unknown by Google. Whenever the liquid in the gas becomes too heavy due to condensation, it can no longer defy gravity and falls in the form of rain. This is true for clouds and Febreeze. A common misconception would be that frozen clouds make snowflakes. Yet, that is not the case. Snowflakes form after the water particles become too heavy for the aerosol clouds. After the water falls a little bit into some below freezing air, it freezes and becomes snowflakes. If you spray Febreeze, most of it will float around in the air like clouds and make your house smell good. Some will form into a liquid and rain onto you which is scary. The world may never know

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what goes into Febreeze eliminating the smell of your stinky socks. The world knows it's not too good to have on their skin or in their eyes. A liquid, the dispersed phase, in a liquid, the dispersed medium, creates an emulsion like milk. The physical state of this is liquid. Milk contains water, but it also consists of stuff like fats and lactose. Lactose is a disaccharide sugar made up of galactose and glucose. It is very common to have an intolerance to lactose. Someone that is lactose intolerant becomes very nauseous if they eat anything that has lactose in it because their body cannot digest it. These people are born without the ability of their body to create lactase. Lactase is an essential enzyme for breaking down lactose, especially if you enjoy eating ice cream. Those who are lactose intolerant are in luck. Lactose-free dairy products do exist. Everyone knows they don’t taste as good, though. A liquid, the dispersed phase, in a solid, the dispersed medium, creates gelatin. If you jiggle Jell-O, you will notice that your hands become wet. But Jell-O isn’t a liquid and it isn’t solid. It’s a gel colloid. Do you drink Jell-O or do you eat it? The same goes for ranch. At my job, we are to change trash that has liquid in them. My coworkers and I always get into the argument about whether ranch is a liquid or not. In all reality, it is a gel. A liquid, the dispersed phase, in a solid, the dispersed medium, also can create solid emulsions like butter. If you touch butter, it is going to make your hands greasy and water does not get it off because the solid fats are hydrophobic. That’s why soap exists. The hydrophobic ends of soap connect to the hydrophobic butter and the hydrophilic ends of soap connect to water. This creates oil, which suspends in the water, cleaning your hands. Thanks, soap. A gas, the dispersed phase, in a liquid, the dispersed medium, makes whipped cream or shaving cream called foam colloids. The physical state of this is liquid. The gas used in the whipping of cream is N2O, nitrous oxide. When shaken, a whipped cream canister makes the

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sound as if a liquid is in there. The canister, pressurized with nitrous oxide, disperses N2O into the cream when activated, creating a delicious foam. Shaving cream works the same way, but it doesn’t taste as good. Many people use the N2O chargers, made for making whipped cream, for getting high, called doing whip-its. A gas, the dispersed phase, in a solid, the dispersed medium, makes marshmallows, a solid foam. The physical state of this is solid. Marshmallows are also very delicious and like whipped cream, you can make marshmallows at home. Homemade marshmallows are also a lot safer in general because there is no N2O to get high. All you need is some gelatin, sugar, syrup, vanilla extract, and a good YouTube video. Colloids are weird. They can feel wet like a liquid and be solid at the same time, like a gel. They can be solids floating around in a gas like an aerosol. Colloids take on many characteristics. Some are even illegal like lead paint. Some taste super good and others look super cool. When it all boils down, colloids are important because they are a part of our everyday life and explain about half of the questions a little kid will ask.

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Works Cited Butler, Kathryn M., and George W. Mulholland. Generation and Transport of Smoke Components. Kluwer, 2004.

EPA. “Federal Action Plant to Reduce Childhood Lead Exposure.” United States Environmental Protection Agency, 19 Dec. 2018, www.epa.gov/lead/federal-action-plan-reducechildhood-lead-exposure....