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These ideas were originally presented at the Leader Training Day 10 October 2009

Science of sherbet

Ingredients:

• 1 teaspoon of citric acid in powder or crystal form
• 1 teaspoon of bicarbonate of soda
• 1 cup of icing sugar lollipop or something similar to dip

Method

• Add the first three ingredients in bowl making sure there are no lumps, sieve if necessary.
• Gently stir until thoroughly mixed.
• Enjoy the sherbet

The science

Citric acid + bicarbonate of soda --> Sodium citrate + water + carbon dioxide.

When the two powders mix with the saliva on your tongue, they react to form sodium citrate, water and carbon di-oxide.  It is the carbon di-oxide bubbles that produce the fizzy sensation on your tongue.

The reaction absorbs heat from your tongue to make it happen, so your tongue will also feel cooler.  This is because the reaction is endothermic (heat absorbing).

 

Growing Sugar Crystals

Ingredients

• 100ml water
• 200gm granulated sugar
• skewers

Method

• Add the sugar to a pan and add the water.
• Heat until boiling and the solution is clear.
• Wet the tip of the skewer and dip in some more sugar making sure a few crystals are stuck to the skewer.
• Pour the dissolved sugar solution into a jar, carefully put the skewer in cover to keep the dust out.
• Leave to cool and the crystals will form.

The Science

A crystal is a large collection of particles arranged in an orderly fashion. The larger the crystal the more particles it contains. Cooling a solution slowly is the best way of getting large crystals.

The picture on the left is what sugar looks like when you dissolve it into your cup of tea. If you add lots more sugar, it continues to dissolve and when enough sugar has dissolved in the water, it looks like the picture on the right. There are enough particles in the solution that some of them will bump into each other and join together (nucleation). When enough particles have clumped together, they will attract others in the solution and the crystal begins to 'grow'. If the particles find a seed crystal (one put in deliberately), the particles attach themselves to it and the crystals grow on it.

Image used with permission from Science Buddies, When Science is Sweet: Growing Rock Candy Crystals

 

Balloon Rockets

You will need:

• sheets of paper
• thin balloons (modelling ones are ideal)

Method

• Decorate a sheet of paper and then make a tube from it with the decoration on the outside.
• Make a nose cone and fins and attach them as shown.
• Insert a narrow balloon and blow up, do not tie the end but hold on to it.
• Launch the rocket by letting go of the balloon, being careful to not point it at anyone.

             T

The Science

Rockets work using Newtons 3rd Law.  As the hot gases push out of the rocket (the action), these gases push the rocket the other way (the reaction).

With a balloon rocket, the gas is the air in the balloon and as that is expelled, the rocket is pushed in the opposite direction.

A space rocket works in basically the same way as a balloon rocket except that a space rocket burns a fuel that creates a compressed gas.  It doesn't expel all the compressed gas at once but continuously burns fuel to resupply the compressed gas and keep the reaction going over a longer period of time.

with acknowledgement to http://home.howstuffworks.com/paper-airplanes9.htm

 

Making compasses

You will need:

• steel pins
• magnets
• small squares of foil/ thin slices of cork
• bowl of water

Method

• Hold the pin carefully and with the magnet stroke the pins in one direction only about 20 times.
• Carefully put the pin through the foil square so its lays flat.
• Put the foil and pin on the surface of the water in the centre of the bowl.
• The foil and pin should rotate and move towards the edge of the bowl.
• Now use the magnet on the outside of the bowl and watch the foil and pin either be attracted or repelled.
• Flip the magnet over so the other end is closest to the bowl, the opposite should now happen.

           

 

The Science

Steel is one of four magnetic materials, the others are iron, cobalt and nickel. They contain 'grains' that act like 'mini magnets' which are randomly arranged. By stroking the pins in one direction only, these 'mini magnets' all line up in the same direction producing a larger magnet.

A compass needle is a magnet which has a north and south pole. The south pole of the magnet is attracted to the north pole of the earth, (it is known as the North seeking pole).

with acknowledgement to http://adventure.howstuffworks.com/compass1.htm

 

Chromatography

You will need:

• 4-5 different black pens (felt tips, roller balls etc. not biros)
• filter paper (coffee filter papers will work)
• cups, beakers

Method

• Cut strips of filter paper about 4-5cm wide by 10-12cm long. Draw a pencil line about 1cm up from the lower edge. On this line draw a small, concentrated dot or a line with one of the range of different pens. Let it dry.
• Attach the other end with a small piece of tape to a pencil so that when the paper is put in the cup, the pencil rests on the rim and the paper is suspended just above the bottom.
• Remove the paper and put a little water in the cup.
• Lower the paper in but make sure that the ink is above the level of the water. Watch the colours separate.
• When they reach near the top of the paper, take it out and let it dry.

The Science

The different molecules in the ink have different characteristics such as size and solubility. Solubility is their ability to dissolve in different fluids such as water or nail polish remover. The fluids that the molecules dissolve in are called solvents.

Because of the different characteristics of the molecules in the ink, they travel at different speeds when pulled along a piece of paper by a solvent (in this case, water).

For example, black ink contains several colours. When the water flows through a word written in black, the molecules of each one of the colours behave differently, resulting in a sort of “rainbow” effect.

You could use this as part of a whodunnit. Write a cryptic note in one black pen, take a small part of it and separate the colours. Ask them to work out which pen wrote the note.

with acknowledgement to http://www.itsjustabox.com/Sciencefair.htmhttp://en.allexperts.com/q/Science-Kids-3250/chromatography-2.htm

 

Bath Bombs

You will need:

• Body glitter/ pot pourri (optional)
• Baby Oil
• Lavender oil (optional)
• 1 and ½ cup (375 ml) Bicarbonate of Soda
• ½ cup (125ml Citric Acid (available from your local pharmacist)
• Fairy cake tray
• Paper cake cases (small cake or mini muffin)
• 2 mixing bowls
• 1 small glass jar
• Rubber gloves

Method

• Sift the bi-carbonate of soda and citric acid into a bowl and mix thoroughly, add the glitter at this stage if wanted.
• Take ½ cup of the base mixture and put it in another bowl.
• In a small glass jar mix a few drops of scented oil with about 4-5 teaspoons of baby oil.
• Using the rubber gloves add the oil mixture to the ½ cup of dry mixture and mix together quickly until it stays together in your hands without crumbling easily. Use a little more baby oil if you need it.
• Using a spoon, press it into the cake cases and press down firmly.
• Repeat with the remaining dry mixture.
• Leave the bath bombs to dry somewhere warm overnight.

The Science

The citric acid reacts with the bicarbonate of soda when the bath bombs are dropped into water producing thousands of bubbles of carbon dioxide which makes the fizz. The oil gives it a lovely scent

with thanks to www.syngenta.co.uk

Has any unit made bath bombs - if so and you have a picture of the activity, Sygenta would love to hear about it. Contact the County Webmaster please.

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