In This Issue:
When the weather keeps you from going outside, you can still have some fun by doing chemistry inside! Try the science projects below to see how chemistry is used to make some everyday things that are fun and enjoyable to have around.
Science Project: Bath Salts and Soft Water
Not just the scents are at work here to make your bath more relaxing. Try this project and learn what salts can do.
You may have noticed that it was much easier to form lather (and more of it!) when using the water with salt rather than the water with no salt. This is because of the difference between hard water and soft water.
Most households in America have hard water. Hard water has a high mineral content, usually with calcium and magnesium, whereas soft water contains very little if any of these minerals. Generally, hard water is not a problem until it is used for cleaning purposes. The problem lies in the calcium and magnesium ions in the hard water - they react with the soap, forming insoluble gray flakes called soap scum rather than a lather. This results in more soap needed to get clean and the bathtub getting a grimy ring around it from the leftover soap scum. One way to soften hard bath water is to add bath salts. The calcium and magnesium ions in the water are replaced with sodium and potassium ions from the salt, allowing the soap to lather much more easily. (If your home has soft water, you may not notice too much of a difference in how well the soap lathers in the water with your bath salts and the water without the bath salts.)
Another benefit of adding salts to your bath has to do with osmosis. Osmosis is the movement of water through a membrane (such as your skin) to achieve equilibrium. Your body contains water and salt, whereas an ordinary bath contains mainly water and very little salt. Therefore, water will pass through your skin in an effort to balance the concentration of water and salt in you and in your bath. This excess water causes pruning. Adding bath salts to the water causes a more equal balance of salt and water in both you and in the bath, so less water enters your skin and less wrinkling occurs.
Science Project: How Does Acid Keep an Apple Fresh?
Apples and pears are great for snacks or to have as a side dish for dinner. But keeping them looking white and delicious after they have been sliced can be tricky. Try this experiment to see how chemistry can keep your apples and pears fresh even after they have been sliced.
When an apple is cut open, an enzyme called polyphenol oxidase is released from the cells of the apple and reacts with the oxygen in the air. This reaction causes the fruit to turn brown, similar to rust forming on metal. Almost all plants contain polyphenol oxidase, and it is believed plants use this enzyme as part of a defense mechanism. When a plant is damaged, the browning of the affected area is thought to discourage animals and insects from eating the plant any further. It also might help the plant heal because the browning creates an antibacterial effect, preventing germs from destroying the plant even more.
Lemon juice helps keep the apple from browning, because it is full of ascorbic acid (Vitamin C) and it has a low (acidic) pH level. Ascorbic acid works because oxygen will react with it before it will react with the polyphenol oxidase. However, once the ascorbic acid gets used up, the oxygen will start reacting with the enzyme and browning will occur. Lemon juice's low pH level also helps prevent browning. Polyphenol oxidase works best when the pH level is between 5.0 and 7.0. However, below a pH level of 3.0, the enzyme becomes inactivated. The pH of lemon juice is in the 2.0 range, making it very effective against browning.
Besides lemon juice, lime juice and cranberry juice also have a pH below 3.0. Concord grape juice and grapefruit juice also have a low pH (not quite as low as the others), but will still help delay the browning process. You may want to try several of these juices and find a tasty to way to serve sliced apples and pears in the process!
Science Project: Make a Colorful Bouncy Ball
Polymers are used to make numerous things, including clothing, plastic containers, nonstick cookware, and bulletproof vests. Try this experiment to see how polymers can make a toy.
The white glue contains polyvinyl acetate, a strong and flexible polymer that gives the ball strength. Cornstarch contains amylopectin, a polymer whose shape is best described as 'branched' - it sticks out like the branches of a tree - and gives the ball the property of elasticity. Elasticity allows the ball to return to its original shape after being compressed or stretched, such as when it hits the floor. So instead of splattering everywhere, the ball bounces back up. The borax is needed to help the glue and the starch stick together. This connects the two polymers into a netlike formation, keeping the ball from crumbling or becoming slime when it is bounced.
Science Project: Make Scented Gel Air Fresheners
Polymers have numerous uses and have made our lives much more comfortable. One way is to help make your home smell fresh.
Gel air fresheners are able to scent the air for a long time because gelatin is a polymer. Specifically, the polymer is collagen, a protein that forms a matrix type structure, allowing the gelatin to hold its shape. The fragrance oil particles are suspended in the matrix of the gel, which keeps the scent trapped inside. As the gel evaporates, the scent particles are released from the matrix, causing a continuous scent to be released from the air freshener.
From the Archives: More Chemistry Projects
The science of chemistry began when people known as alchemists tried to turn common metals (such as lead) into gold.
Citric acid is found naturally in fruits and is used as a preservative and flavoring in many foods such as soda, candy, cheese, and powdered drink mixes. Cough syrup, blueprints, and some bath soaps also contain citric acid.
Play this game to learn about which elements are used in items around the house.