As silver oxidizes it will tarnish. This layer of oxidation can be removed without polishing and scrubbing by simply dipping your silver in this non-toxic electrochemical dip. Another big advantage to using a dip is that the liquid can reach places a polishing cloth cannot.

Difficulty: Easy

Time Required: Minutes

Here's How:

Line the bottom of the sink or a glass baking dish with a sheet of aluminum foil. Duct Cleaning Grout Cleaning Clean Cleaning Prices Pressure Cleaning

Fill the foil-lined container with steaming hot water. Add salt (sodium chloride) and baking soda (sodium bicarbonate) to the water. Some recipes call for 2 tsp baking soda and 1 tsp salt, whereas others call for 2 tablespoons each of baking soda and salt. Personally, I wouldn't measure the amounts... just add a bit of each substance. Drop the silver items into the container so that they are touching each other and resting on the foil. You will be able to watch the tarnish disappear. Leave heavily tarnished items in the solution for as long as 5 minutes. Otherwise, remove the silver when it appears clean. Rinse the silver with water and gently buff it dry with a soft towel. Ideally, you should store your silver in a low-humidity environment. You can place a container of activated charcoal or a piece of chalk in the storage area to minimize future tarnish.

Tips:

Use care when polishing or dipping silver plated items. It is easy to wear away the thin layer of silver and cause more harm than good through overcleaning.

Minimize exposing your silver to substances which contain sulfur (e.g., mayonnaise, eggs, mustard, onions, latex, wool) as the sulfur will cause corrosion. Using your silver flatware/holloware or wearing silver jewelry helps to keep it free from tarnish.

What You Need:

Sink or glass pan Hot water Baking soda Salt Aluminum foil Tarnished silver

This is an easy chemistry project that uses common materials. You take a post-1982 penny, score the copper surface to expose the zinc interior, react the zinc with acid, and are left with a hollow copper penny.

What You Need:

post-1982 US pennies (metal composition changed in this year) muriatic acid (from a hardware store)

a disposable plastic container or glass jar baking soda (sodium bicarbonate) water

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Chemistry Zinc Chemical Analysis Distilled Water Acid

Time Required: 6 hours

Here's How:

You need to expose the interior of the pennies. You can score the edge of the pennies with a file or snip them with wire cutters, but I think the easiest way to expose the zinc is to rub the edge of each penny along a brick or concrete block. You could use sandpaper, if it's available. Use whatever is handy to expose some of the zinc (don't go all the way around the coin). If you can see silver metal under the copper of the penny, you're ready to proceed to the next step. It's best to do this step outdoors or under a fume hood, wearing gloves and protective eyewear. Read the safety precautions on the muriatic acid container. Basically, this is hydrochloric acid. Treat it with respect. Place the pennies in your container. Pour a little muriatic acid over the pennies so that they are covered. Bubbles will start to form immediately. Set the container somewhere where it will be safe from spills, children, and pets. Let the reaction proceed for about 6 hours.

Carefully pour off the muriatic acid. You can wash it down a drain, providing you use a lot of water. Fill the container with water. Add a little baking soda to neutralize the residual acid. Examine your penny. The hollow penny will be a fragile copper foil.

Non-newtonian fluids

Have you ever turned a liquid into a solid just by tapping on it? In this experiment you make just such a liquid.

For this experiment you will need:

corn starch (about ¼ cup, or 60 cm3) water (about ¼ cup, or 60 cm3) a bowl for mixing newspaper

Place a sheet of newspaper flat on a table. Put the mixing bowl in the middle of the newspaper. Add ¼ cup of dry cornstarch to the bowl. Add about 1/8 cup (2 tablespoons, or 30 cm3) of water to the corn starch and stir slowly. Add water slowl

y to the mixture, with stirring, until all of the powder is wet.

Continue to add water until the cornstarch acts like a liquid when you stir it slowly. When you tap on the liquid with your finger, it shouldn't splash, but rather will become hard. If your mixture is too liquid, add more cornstarch. Your goal is to create a mixture that feels like a stiff liquid when you stir it slowly, but feels like a solid when you tap on it with your finger or a spoon.

Scoop the cornstarch mixture into the palm of your hand, then slowly work it into a ball. As long as you keep pressure on it by rubbing it between your hands, it stays solid. Stop rubbing, and it �melts� into a puddle in your palm. Can you think of other tests you can do with it?

Why does the cornstarch mixture behave like this?

Think of a busy sidewalk. The easiest way to get through a crowd of people is to move slowly and find a path between people. If you just took a running start and headed straight for the crowd of people, you would quickly slam into someone and you wouldn't get very far. This is similar to what happens in the cornstarch mixture. The solid cornstarch acts like a crowd of people. Pressing your finger slowly into the mixture allows the cornstarch to move out of the way, but tapping the mixture quickly doesn't allow the solid cornstarch particles to slide past each other and out of the way of your finger.

We use the term �viscosity� to describe the resistance of a liquid to flow. Water, which has a low viscosity, flows easily. Honey, at room temperature, has a higher viscosity and flows more slowly than water. But if you warm honey up, its viscosity drops, and it flows more easily. Most fluids behave like water and honey, in that their viscosity depends only on temperature. We call such fluids �Newtonian,� since their behavior was first described by Isaac Newton (when he wasn�t discovering the laws of gravity or developing the calculus). The cornstarch mixture you made is called �non-Newtonian� since its viscosity also depends on the force applied to the liquid or how fast an object is moving through the liquid.

Other examples of non-Newtonian fluids include ketchup, silly putty, and quicksand. Quicksand is like the cornstarch mixture: if you struggle to escape quicksand, you apply pressure to it and it becomes hard, making it more difficult to escape. The recommended way to escape quicksand is to slowly move toward solid ground; you might also lie down on it, thus distributing your weight over a wider area and reducing the pressure. Ketchup is the opposite: its viscosity decreases under pressure. That�s why shaking a bottle of ketchup makes it easier to pour.

Disposal: First dilute the cornstarch mixture with plenty of water before pouring it down the drain. Why? What do think would happen to the semi-solid, semi-liquid form that you prepared if pressure were applied to it by other water in the drain? Yes � a plugged drain.