Experimental Proof for Dark Colour absorbs more Heat

Things You Need
  •  2 identical drinking glasses or jars
  • Water
  • Thermometer
  • 2 elastic bands or some cello-tape
  • White paper
  • Black paper 
The Way You Do
  1. Wrap the white paper around one of the glasses using an elastic band or cello-tape to hold it on.
  2. Do the same with the black paper and the other glass.
  3. Fill the glasses with the exact same amount of water.
  4. Leave the glasses out in the sun for a couple of hours before returning to measure the temperature of the water in each. 
What You Observe

Dark surfaces such as the black paper absorb more light and heat than the lighter ones such as the white paper. After measuring the temperatures of the water, the glass with the black paper around it should be hotter than the other. Lighter surfaces reflect more light, that's why people where lighter colored clothes in the summer, it keeps them cooler. 

Egg Floats in Salt Water  

Things You Need
  • One egg
  • Water
  • Salt
  • A tall drinking glass 

The Way You Do
  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 You Observe 

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.

Melting a Chocolate

Things You need
  • Small chocolate pieces of the same size (chocolate bar squares or chocolate chips are a good idea)
  • Paper plates
  • Pen and paper to record your results 

The Way You Do
  1. Put one piece of chocolate on a paper plate and put it outside in the shade.
  2. Record how long it took for the chocolate to melt or if it wasn't hot enough to melt then record how soft it was after 10 minutes.
  3. Repeat the process with a piece of chocolate on a plate that you put outside in the sun. Record your results in the same way.
  4. Find more interesting locations to test how long it takes for the chocolate pieces to melt. You could try your school bag, hot water or even your own mouth.
  5. Compare your results, in what conditions did the chocolate melt? You might also like to record the temperatures of the locations you used using a thermometer so you can think about what temperature chocolate melts at.

What You Observe 

At a certain temperature your chocolate pieces undergo a physical change, from a solid to a liquid (or somewhere in between). On a hot day, sunlight is usually enough to melt chocolate, something you might have unfortunately already experienced. You can also reverse the process by putting the melted chocolate into a fridge or freezer where it will go from a liquid back to a solid. The chocolate probably melted quite fast if you tried putting a piece in your mouth, what does this tell you about the temperature of your body? For further testing and experiments you could compare white chocolate and dark chocolate, do they melt at the same temperature? How about putting a sheet of aluminium foil between a paper plate and a piece of chocolate in the sun, what happens then?

Mixing Oil and Water

Things You Need
  • Small soft drink bottle
  • Water
  • Food colouring powder
  • 2 tablespoons of cooking oil
  • Dish washing liquid or detergent 

The Way You Do
  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 You Observe 

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

Making Quick Sand 

Things You Need
  • 1 cup of maize cornflour
  • Half a cup of water
  • A large plastic container
  • A spoon 

The Way You Do
  1. This one is simple, just mix the cornflour and water thoroughly in the container to make your own instant quick sand.
  2. When showing other people how it works, stir slowly and drip the quick sand to show it is a liquid.
  3. Stirring it quickly will make it hard and allow you to punch or poke it quickly (this works better if you do it fast rather than hard).
  4. Remember that quick sand is messy, try to play with it outside and don’t forget to stir just before you use it.
  5. Always stir instant quicksand just before you use it!

 What You Observe 

If you add just the right amount of water to cornflour it becomes very thick when you stir it quickly. This happens because the cornflour grains are mixed up and can’t slide over each other due to the lack of water between them. Stirring slowly allows more water between the cornflour grains, letting them slide over each other much easier.

Poking it quickly has the same effect, making the substance very hard.  If you poke it slowly it doesn’t mix up the mixture in the same way, leaving it runny.  It works in much the same way as real quick sand.

Vinegar Volcano 

Things You 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)
  •  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)

The Way You Do
  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 You Observe 

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.

Egg Boiled or Raw 

Things You Need
  • Two eggs, one hard boiled and one raw.
  •  Make sure the hard boiled egg has been in the fridge long enough to be the same temperature as the raw egg.
The Way You Do
  1. Spin the eggs and watch what happens, one egg should spin while the other wobbles.
  2. You can also lightly touch each of the eggs while they are spinning, one should stop quickly while the other keeps moving after you have touched it.
What You Observe 

The raw egg's centre of gravity changes as the white and yolk move around inside the shell, causing the wobbling motion. Even after you touch the shell it continues moving. This is because of inertia, the same type of force you feel when you change direction or stop suddenly in a car, your body wants to move one way while the car wants to do something different. Inertia causes the raw egg to spin even after you have stopped it, this contrasts with the solid white and yolk of the hard boiled egg, it responds much quicker if you touch it.

Glowing Water 

Things You Need
  • A black light (you can find them at places like Walmart and hardware stores, as well as online stores like Amazon).
  • Tonic water or a highlighter pen.
  • A dark room to do the experiment. 

The Way You Do
  1. If you are using a highlighter pen carefully break it open, remove the felt and soak it in a small amount of water for a few minutes.
  2. Find a dark room.
  3. Turn on the black light near your water, how does it look?
What You Observe

Black light (also known as UV or ultra violet light) is a part of the electromagnetic spectrum. The electromagnetic spectrum also includes infrared, X-rays, visible light (what the human eye can see) and other types of electromagnetic radiation. A black light lamp such as the one you used emits a UV light that can illuminate objects and materials that contain phosphors. Phosphors are special substances that emit light (luminescence) when excited by radiation. Your water glowed under the black light because it contained phosphors. If you used a highlighter pen then the UV light reacted with phosphors in the dye. If you used tonic water then the UV light reacted with phosphors in a chemical used in tonic water called quinine.

There are different types of luminescence, they include fluorescence (used in this experiment, it glows only when the black light is on), phosphorescence (similar to fluorescence but with a glow that can last even after the black light is turned off), chemiluminescence (used to create glow sticks), bioluminescence (from living organisms) and many others.

Bathing Salts 

Things You Need
  • 1 cup of washing soda
  • A plastic bag
  • A rolling pin (or something similar that can crush lumps)
  • A bowl
  • A spoon for stirring
  • Essential oil
  • Food coloring powder 

The Way You Do
  1. Take the cup of washing soda and put it into a plastic bag. Crush the lumps with a rolling pin or similar object.
  2. Empty the bag into a bowl and stir in 5 or 6 drops of your favorite essential oil such as rosemary, lavender or mint.
  3. Stir in a few drops of food coloring until the mixture is evenly colored.
  4. Put the mixture into clean dry containers and enjoy as you please. 

What You Observe 

Bath Salts are typically made from Epsom salts (magnesium sulfate), table salt (sodium chloride) or washing soda (sodium carbonate). The chemical make up of the mixture makes it easy to form a lather. Bath salts are said to improve cleaning and deliver an appealing fragrance when bathing.

Breeding Bacteria

Things You Need
  • Petri dish of agar
  • Cotton buds
  • Some old newspaper (to wrap petri dish when disposing)
The Way Do
  1. Prepare your petri dish of agar.
  2. Using your cotton bud, swab a certain area of your house (i.e. collect a sample by rubbing the cotton bud on a surface of your choice).
  3. Rub the swab over the agar with a few gentle strokes before putting the lid back on and sealing the petri dish.
  4. Allow the dish to sit in a warm area for 2 or 3 days.
  5. Check the growth of the bacteria each day by making an observational drawing and describing the changes.
  6. Try repeating the process with a new petri dish and swab from under your finger nails or between your toes.
  7. Dispose of the bacteria by wrapping up the petri dish in old newspaper and placing in the rubbish (don't open the lid) 

What You Observe 

The agar plate and warm conditions provide the ideal place for bacteria to grow. The microorganisms on the plate will grow into individual colonies, each a clone of the original. The bacteria you obtained with the cotton bud grows steadily, becoming visible with the naked eye in a relatively short time. Different samples produce different results, what happened when you took a swab sample from your own body?

You will find bacteria throughout the Earth, it grows in soil, radioactive waste, water, on plants and even animals too (humans included). Thankfully for us, our immune system usually does a great job of making bacteria harmless.

Breeding Potato using Straw

Things You Need
  • Stiff plastic drinking straws
  • A raw potato

The Way You Do
  1. Hold a plastic drinking straw by it sides (without covering the hole at the top) and try quickly stabbing the potato, what happens?
  2. Repeat the experiment with a new straw but this time place your thumb over the top, covering the hole. 

What You Observe 

Placing your thumb over the hole at the top of the straw improves your ability to pierce the potato skin and push the straw deep into the potato. The first time you tried the experiment you may have only pierced the potato a small amount, so why are you more successful on the second attempt?

Covering the top of the straw with your thumb traps the air inside, forcing it to compress as you stab the straw through the potato skin. This makes the straw strong enough to pierce the potato, unlike the first attempt where the air is pushed out of the straw.

Effect of Heat on Dissolving Sugar

Things You Need
  • Sugar cubes
  • Cold water in a clear glass
  • Hot water in a clear glass (be careful with the hot water)
  • Spoon for stirring

The Way You Do
  1. Make sure the glasses have an equal amount of water.
  2. Put a sugar cube into the cold water and stir with the spoon until the sugar disappears. Repeat this process (remembering to count the amount of sugar cubes you put into the water) until the sugar stops dissolving, you are at this point when sugar starts to gather on the bottom of the glass rather than dissolving.
  3. Write down how many sugar cubes you could dissolve in the cold water.
  4. Repeat the same process for the hot water, compare the number of sugar cubes dissolved in each liquid, which dissolved more?

What You Observe 

The cold water isn't able to dissolve as much sugar as the hot water, but why? Another name for the liquids inside the cups is a 'solution', when this solution can no longer dissolve sugar it becomes a 'saturated solution', this means that sugar starts forming on the bottom of the cup.

The reason the hot water dissolves more is because it has faster moving molecules which are spread further apart than the molecules in the cold water. With bigger gaps between the molecules in the hot water, more sugar molecules can fit in between. 


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