Background

The general ruls of solubility is that ”like dissolves like”. This means that polar solvents like water will dissolve more polar compounds such as ionic compounds like salts (e.g. sodium chloride). Less polar solvents such as organic solvents (e.g. propanone) will dissolve non-polar compounds such as plastics.

Nail polish contains non-polar compounds. Nail polish remover is made from propanone, a non-polar solvent which will dissolve nail polish, but not the polar ionic compound sodium chloride.

Method

1. Collect two watch glasses. 2. Brush some nail polish into the middle of the two watch glasses and let it dry. 3. Collect one beaker with water and fill a second beaker with propanone or nail polish remover. 4. Drop ¼ spatula of salt into the beaker containing water and stir. Observe what happens. 5. Drop ¼ spatula of salt into the beaker containing propanone and stir. Observe what happens. 6. Drop water onto one watch glass with nail polish and watch what happens. 7. Then drop some propanone or nail polish remover onto the 2nd watch glass with nail polish and watch what happens.

Results Table

Create your own results table.

Analysis

1. Explain your results. 2. What are weaknesses of the experiment? 3. How could you improve the experiment?

You will need:

• Kitchen roll
• Felt tip pens
• Water
• Bowl or cup
• Scissors

What to do:

1. Cut a long strip from one sheet of kitchen roll. It should be 2 cm or 1 inch wide.
2. Choose one felt tip pen and draw a big dot at the bottom of your kitchen roll strip. IMPORTANT: Do not draw the dot all the way at the bottom, leave about 2 to 3 cm from the bottom to the dot.
3. Pour some water into a bowl or cup.
4. Place the bottom of your kitchen roll strip in the water and watch what happens. IMPORTANT: When you do this, the dot must be above the water.
5. Repeat the method with other felt tip pens.

Background

The inks in felt tip pens are made by mixing different colouring materials, called “pigments”. We can use chromatography separate the different colours because some are soaked up the kitchen roll faster than others.

The reason is that the different pigments have different solubilities in water. The further the colour travels, the more soluble it is. Less soluble colours stay at the bottom.

You can watch a video of this experiment here:

You will need

• 1 Sauce pan
• 1 Chopping board
• 1 Knife
• 1 large glass jar
• 4 small glass jars
• 1 Red Cabbage
• Vinegar, lemon juice, water and bicarbonate of soda to test

What to do

1. Carefully chop the red cabbage leaves into small pieces on the chopping board.
2. Put the red cabbage in a sauce pan and add water until the red cabbage leaves are completely covered.
3. Gently boil the red cabbage for 10 to 15 minutes.
4. After the sauce pan has cooled down, collect the water in a large jar.
5. To better see the red cabbage water’s colour add some water to dilute it.
6. Transfer the red cabbage water into the 4 small jars.
7. Add a dash of vinegar to the first small jar with red cabbage juice and observe what happens.
8. Repeat step 7 for the other substances you want to test. Each substance goes into a new small jar with red cabbage juice.
9. What colour changes do you observe?

Background

Red cabbage juice is a pH indicator. This means it changes colour depending on if it is in an acidic, alkaline or neutral environment. In this experiment you are testing some acids (vinegar and lemon juice), some alkalis (bicarbonate of soda) and a neutral substance (water).

Which colour changes can you observe in your experiment? What colour does red cabbage indicator have in acids, bases or with neutral substances?

You can watch this experiment as a video here:

You will need

• Candle
• Matches or lighter
• 3 Jars of different sizes
• Heatproof base, for example a ceramic plate
• Stopwatch/timer (your mobile phone will do)

What to do

1. Put the candle on the heatproof base and light it.
2. Put the smallest jar upside down over the candle and start the timer.
3. Time how long it takes for the candle to go out and record the time.
4. Repeat steps 2 and 3 for the medium sized jar and the large jar.
5. Record for each candle how long it burns. Under which jar does the candle burn longest?

Background

Oxygen is needed for a fire to burn. This is also true for candles. The oxygen is normally supplied by the air.

When placing a jar over the candle, the amount of oxygen for the candle is limited. The candle goes out when all oxygen in the jar is used up. The amount of oxygen depends on the size of the jar.

Under which jar does the candle burn longest? Why do you think that is?

You can watch a video of this experiment here:

You will need

• Short length of wool or string
• Warm water
• 2 Paperclips
• 1 Plate
• 1 Spoon
• 2 Glass jars
• Washing soda

What to do

1. Fill both jars with warm water. (From the tap is fine.)
2. Add washing soda to both jars and stir until no more washing soda dissolves.
3. Attach a paperclip to each end of the string or wool.
4. Place the ends of the string in the jars, so the string hangs between the jars.
5. Place a plate between the jars to catch the drips of the solution flowing along the string or wool.
6. Leave the jars for one to two weeks in a safe place and observe what happens.

Background

The washing soda solution slowly soaks the string or wool and flows along it. As the solution drips off some washing soda is deposited slowly forming a crystal.

Water flowing underground dissolves minerals when it seeps through rocks. The minerals are deposited when the water drips of a cave roof. A crystal is formed that hangs off the cave rood which we call “stalactite”. When the water drips to the floor it deposits minerals there forming a crystal growing up from the ground which we call “stalagmite”.

In your experiment a stalactite grows hanging from the string or wool.

You can watch a video of this experiment:

You will need

• 1 Sharp knife
• Matches
• Heat proof surface, for example a pan or a ceramic plate
• 1 Potato
• 1 Peanut
• 1 Almond
• 1 Walnut
• If you are allergic to nuts you can use sunflower and pumpkin seeds instead.

What to do

1. Cut a potato into a long cylinder or a tall rectangular cube.
2. Carefully cut a long thin strip from the peanut, almond and walnut.
3. Stick 1 peanut strip into the top of the potato. The potato will hold the peanut while it is burning.
4. Light the peanut strip with a match. Let it burn until it goes out.
5. Repeat steps 3 and 4 with one almond and one walnut strip.
6. Which nut burns longest? Which nut is easiest to light?

Background

Nuts contain oil that can be lit to create a fire. The oil and the oxygen from the air undergo a chemical change during the fire turning them into carbon dioxide gas and steam. This type of reaction producing a fire is called “combustion”.

The nut that lights fastest and burns longest contains most oil. Which nut contained most oil?

You can watch a video of the experiment here:

Background

Vinegar is an acid and reacts with baking soda to form salt, water and carbon dioxide gas. The extremely fast formation of carbon dioxide gas will cause your zipper back bomb to explode.

You will need

• Plastic zipper bag
• Vinegar (any kind will do, but you will need quite a lot of it)
• Baking soda
• Cup, glass or mug
• Table spoon

What to do

1. Go outside to do this experiment.
2. Check your zipper bag to make sure that it does NOT have any holes or rips before the experiment.
3. Fill your glass or mug completely with vinegar
4. Pour the vinegar from your glass or mug into the plastic zipper bag.
5. Place the zipper bag on the ground.
6. Add one heaped table spoon of baking soda and quickly close the bag.
7. Quickly step away from the zipper bag and watch what happens.

You can watch this experiment here:

Background

Diffusion is the movement of particles from a place of high concentration to a place of low concentration. We can also say that particles move from where there are lots of particles to where there are less particles.

In this experiment we are going to look at the diffusion of colour particles. You will observe the colour moving away from the sweets where lots of colour particles are found to places with less colour particles in the middle of the plate.

You will need

• M&Ms or Smarties
• Plate
• Water

What to do

1. Once you start this experiment, you cannot move it. So, make sure you choose a good spot to start.
2. Pour the bag of M&Ms or Smarties onto your plate.
3. Remove the sweets that landed in the middle of your plate.
4. Place the remaining sweets in a circle around the outside of your plate.
5. Remove any remaining M&Ms or Smarties that do not fit in the circle.
6. Slowly add water to your plate. It needs to reach the M&Ms, but they should not float. From now on you cannot move the experiment.
7. Observe what happens to the colour of the sweets.

You can also watch this experiment on YouTube: