Fun With Science

Index: Science Experiments: Dry Ice Bubble Parachute Making Orange: Floats Or Sinks Invisible Ink Gravity Free Water Scientific Facts

Science Experiments

Make a Big Dry Ice Bubble What you'll need: Water A large bowl with a lip around the top (a smaller bowl or cup will work too) A strip of material or cloth Soapy mixture for making bubbles (water and some dishwashing liquid should do the trick) Dry ice - one piece for a cup, more for a bowl. Places where adults can buy dry ice include large grocery stores and Walmart. Butchers and ice cream stores might have some too. Safety first!  Be careful with dry ice as it can cause skin damage if not used safely. Adults should handle dry ice with gloves and avoid directly breathing in the vapor.

Instructions: Place your dry ice in the bowl and add some water (it should start looking like a spooky cauldron). Soak the material in your soapy mixture and run it around the lip of the bowl before dragging it across the top of the bowl to form a bubble layer over the dry ice. Stand back and watch your bubble grow! What's happening? Dry ice is carbon dioxide (CO2) in its solid form. At temperatures above -56.4 °C (-69.5 °F), dry ice changes directly from a solid to a gas, without ever being a liquid. This process is called sublimation. When dry ice is put in water it accelerates the sublimation process, creating clouds of fog that fill up your dry ice bubble until the pressure becomes too much and the bubble explodes, spilling fog over the edge of the bowl. Dry ice is sometimes used as part of theater productions and performances to create a dense foggy effect. It is also used to preserve food, freeze lab samples and even to make ice cream!  

Design and Test a Parachute What you'll need: A plastic bag or light material Scissors String A small object to act as the weight, a little action figure would be perfect  

Instructions: Cut out a large square from your plastic bag or material. Trim the edges so it looks like an octagon (an eight sided shape). Cut a small whole near the edge of each side. Attach 8 pieces of string of the same length to each of the holes. Tie the pieces of string to the object you are using as a weight.

What's happening??? Hopefully your parachute will descend slowly to the ground, giving your weight a comfortable landing. When you release the parachute the weight pulls down on the strings and opens up a large surface area of material that uses air resistance to slow it down. The larger the surface area the more air resistance and the slower the parachute will drop. Cutting a small hole in the middle of the parachute will allow air to slowly pass through it rather than spilling out over one side, this should help the parachute fall straighter.

Does an Orange Float or Sink? What you'll need: An orange A deep bowl or container Water   Instructions: Fill the bowl with water. Put the orange in the water and watch what happens. Peel the rind from the orange and try the experiment again, what happens this time?

What's happening? The first time you put the orange in the bowl of water it probably floated on the surface, after you removed the rind however, it probably sunk to the bottom, why? The rind of an orange is full of tiny air pockets which help give it a lower density than water, making it float to the surface. Removing the rind (and all the air pockets) from the orange increases its density higher than that of water, making it sink. Density is the mass of an object relative to its volume. Objects with a lot of matter in a certain volume have a high density, while objects with a small amount of matter in the same volume have a low density.

Invisible Ink with Lemon Juice What you'll need: Half a lemon Water Spoon Bowl Cotton bud White paper Lamp or other light bulb

Instructions: Squeeze some lemon juice into the bowl and add a few drops of water. Mix the water and lemon juice with the spoon. Dip the cotton bud into the mixture and write a message onto the white paper. Wait for the juice to dry so it becomes completely invisible. When you are ready to read your secret message or show it to someone else, heat the paper by holding it close to a light bulb.  

What's happening? Lemon juice is an organic substance that oxidizes and turns brown when heated. Diluting the lemon juice in water makes it very hard to notice when you apply it the paper, no one will be aware of its presence until it is heated and the secret message is revealed. Other substances which work in the same way include orange juice, honey, milk, onion juice, vinegar and wine. Invisible ink can also be made using chemical reactions or by viewing certain liquids under ultraviolet (UV) light.

Gravity Free Water What you'll need: Instructions: A glass filled right to the top with water A piece of cardboard   Instructions: Put the cardboard over the mouth of the glass, making sure that no air bubbles enter the glass as you hold onto the cardboard. Turn the glass upside down (over a sink or outside until you get good). Take away your hand holding the cardboard.

What's happening? If all goes to plan then the cardboard and water should stay put. Even though the cup of water is upside down the water stays in place, defying gravity! So why is this happening? With no air inside the glass, the air pressure from outside the glass is greater than the pressure of the water inside the glass. The extra air pressure manages to hold the cardboard in place, keeping you dry and your water where it should be, inside the glass.

Science Facts

Hydrogen is the first element on the periodic table Hydrogen is the first element on the periodic table. It has an atomic number of 1. It is highly flammable and is the most common element found in our universe. Liquid nitrogen boils at 77 kelvin (−196 °C, −321 °F). Around 1% of the sun’s mass is oxygen. Helium is lighter than the air around us so it floats, that's why it is perfect for the balloons you get at parties. Carbon comes in a number of different forms (allotropes), these include diamond, graphite and impure forms such as coal. Under normal conditions, oil and water do not mix.

Although it is still debated, it is largely recognized that the word 'chemistry' comes from an Egyptian word meaning 'earth'. The use of various forms of chemistry is believed to go back as long ago as the Ancient Egyptians. By 1000 BC civilizations were using more complex forms of chemistry such as using plants for medicine, extracting metal from ores, fermenting wine and making cosmetics. Things invisible to the human eye can often be seen under UV light, which comes in handy for both scientists and detectives. Humans breathe out carbon dioxide (CO2). Using energy from sunlight, plants convert carbon dioxide into food during a process called photosynthesis. Chemical reactions occur all the time, including through everyday activities such as cooking. Try adding an acid such as vinegar to a base such as baking soda and see what happens!

Above 4 °C, water expands when heated and contracts when cooled Above 4 °C, water expands when heated and contracts when cooled. But between 4 °C and 0 °C it does the opposite, contracting when heated and expanding when cooled. Stronger hydrogen and oxygen bonds are formed as the water crystallizes into ice. By the time it's frozen it  takes up around 9% more space. Often formed under intense pressure over time, a crystal is made up of molecules or atoms that are repeated in a three dimensional repeating pattern. Quartz is a well known example of a crystal. Athletes at the Olympic Games have to be careful how much coffee they drink. The caffeine in coffee is a banned substance because it can enhance performance. One or two cups are fine but they can go over the limit with more than five. (update - as of 2004 caffeine has been taken back off the WADA banned list but its use will be closely monitored to prevent future abuse by athletes.)

By- Aditri Narula VII-A Delhi Public School Ghaziabad International