domingo, 8 de janeiro de 2012

Chemical Experiments I

Alguns experimentos de quimica. Além de ser uma ótima atividade de leitura e interpretação de texto é uma ótima oportunidade para realizar um projeto interdisciplina com os docentes de quimica.

# 1 - Mixing Oil and Water

Some things just don't get along well with each other. Take oil and water as an example, you can mix them together and shake as hard as you like but they'll never become friends.....or will they? Take this fun experiment a step further and find out how bringing oil and water together can help you do your dishes.

 What you'll need:

     * Small soft drink bottle

    * Water

    * Food colouring

    * 2 tablespoons of cooking oil

    * Dish washing liquid or detergent


   1. Add a few drops of food colouring to the water.

   2. Pour about 2 tablespoons of the coloured water along with the 2 tablespoons of cooking oil into the small soft drink bottle.

   3. Screw the lid on tight and shake the bottle as hard as you can.

   4. Put the bottle back down and have a look, it may have seemed as though the liquids were mixing together but the oil will float back to the top.

 What's happening?

While water often mixes with other liquids to form solutions, oil and water does not. Water molecules are strongly attracted to each other, this is the same for oil, because they are more attracted to their own molecules they just don't mix together. They separate and the oil floats above the water because it has a lower density.

If you really think oil and water belong together then try adding some dish washing liquid or detergent. Detergent is attracted to both water and oil helping them all join together and form something called an emulsion. This is extra handy when washing those greasy dishes, the detergent takes the oil and grime off the plates and into the water, yay!

# 2 -  Make an Egg Float in Salt Water

 An egg sinks to the bottom if you drop it into a glass of ordinary drinking water but what happens if you add salt? The results are very interesting and can teach you some fun facts about density.

What you'll need:

     * One egg

    * Water

    * Salt

    * A tall drinking glass


    1. Pour water into the glass until it is about half full.

   2. Stir in lots of salt (about 6 tablespoons).

   3. Carefully pour in plain water until the glass is nearly full (be careful to not disturb or mix the salty water with the plain water).

   4. Gently lower the egg into the water and watch what happens.

What's happening?

 Salt water is denser than ordinary tap water, the denser the liquid the easier it is for an object to float in it. When you lower the egg into the liquid it drops through the normal tap water until it reaches the salty water, at this point the water is dense enough for the egg to float. If you were careful when you added the tap water to the salt water, they will not have mixed, enabling the egg to amazingly float in the middle of the glass. 

# 3 - Baking Soda & Vinegar Volcano

Use baking soda and vinegar to create an awesome chemical reaction! Watch as it rapidly fizzes over the container and make sure you've got some towels ready to clean up.

What you'll need:

    * Baking Soda (make sure it's not baking powder)

    * Vinegar

    * A container to hold everything and avoid a big mess!

    * Paper towels or a cloth (just in case)


   1. Place some of the baking soda into your container.

   2. Pour in some of the vinegar

   3. Watch as the reaction takes place!

What's happening?

 The baking soda (sodium bicarbonate) is a base while the vinegar (acetic acid) is an acid. When they react together they form carbonic acid which is very unstable, it instantly breaks apart into water and carbon dioxide, which creates all the fizzing as it escapes the solution.

For extra effect you can make a realistic looking volcano. It takes some craft skills but it will make your vinegar and baking soda eruptions will look even more impressive!


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