How to make a raw egg bounce?

How can you make a raw egg bounce? Is it possible? Read on to find out...

Materials:

• 1 raw egg
• 1 bottle of white vinegar
• 1 container / bowl
• water

Steps:
1. Place an egg into a container / bowl.

2. Pour white vinegar into the container until the eggs are completely submerged. Observe what happens.

3. Change the vinegar on the second day and subsequent days for a week.

4. Pour the vinegar away and rinse the egg with water.

5. Observe what happens to the egg.

6. Bounce the egg.

Note: You can place the egg in vinegar for about 48 hours and the egg will still be able to bounce.

Video:

Watch a video on the experiment.

Teacher Serena's Explanations:

When vinegar is poured into the container, bubbles are seen forming on the shell. The bubbles contain carbon dioxide. Why? Vinegar is an acid while egg shells are made up of calcium carbonate. The vinegar reacts with the calcium carbonate by breaking the chemical into the simplest parts, the calcium part and the carbonate part. The calcium part floats around in the solution while the carbonate part reacts to form carbon dioxide bubbles on the shell.

Some of the vinegar will pass through the membrane of the egg, causing the egg to become slightly bigger. This process is known as osmosis. Osmosis is the flow of a liquid from one solution through a semi-permeable membrane into another less concentrated solution.

~ Serena's Greenhouse

Informative Video on DNA and genes

Found an informative clip that explains what DNA and genes are. It is clear and easy to understand. Good for kids who want to learn beyond the Science syllabus! Highly recommended.

Why can birds perch on power lines without being electrocuted?

One of my pupils asked me this interesting question: why can birds perch on power lines without being electrocuted?

Here's the scientific explanation:
Birds usually perch on a single power line. Hence, there is no potential difference between the two feet and no electric current will flow through the bird.

For the bird to be electrocuted, a potential difference must exist across its two feet. If the bird touches two power lines at a time, or one power line and a ground wire or the Earth, the bird would be electrocuted and die.

Many large birds such as eagles and vultures can be electrocuted when their wide wings touch a power line and a ground wire at the same time.

Let's watch a video that explains this phenomenon through an experiment:

A word of advice:Do not fly a kite near power lines. If the kite gets tangled in the power lines, the kite string acts as a ground and you can be electrocuted.


~ By Serena's Greenhouse

Bad Hair Day?

Have you walked across a carpet and then felt a stinging sensation when you touched a door knob? What causes this tingling sensation? Have you combed your hair and still find them standing on end? What causes the hair to stand? The answer is static electricity.


What is static electricity?

All matter is made of atoms. An atom has three types of particles: (1) positively charged particles called protons (2) negatively charged particles called electrons and (3) particles with a neutral charge called neutrons.


Some materials such as nylon and hair lose electrons very easily. Have you combed your hair and realised that they are standing on end? When you run a dry comb through your hair, your hair loses some of its electrons to the comb. Hence your hair becomes positively charged while the comb becomes negatively charged. Your hair will stand on end as each strand of hair is positively charged and repel each other. Like charges repel each other, just like like poles repel each other in magnets.


The triboelectric series ranks materials by how easily they give up electrons. Hair and nylon are at the top of the series as they lose electrons easily. Scotch tape and Teflon are at the bottom as they grab electrons.

Watch a video on how a Van de Graaff Generator make hair stand

How does a Van de Graaff Generator work?

A Van de Graaff generator consists of a few parts: a motor, a belt, two rollers (the bottom roller can be made of nylon and the upper roller can be made of Teflon), two combs and a metal sphere. As the motor turns, the rubber belt first goes over the nylon roller. One comb pulls electrons from the nylon which loses electrons easily and transfers them to the rubber belt. The rubber belt then travels to the Teflon roller. The second comb collects the electrons from the belt and stores them on the metal sphere. Hence the sphere quickly collects a lot of electrons and becomes negatively charged.

When we touch the metal sphere while standing on an insulated material, the electrons will flow through our body and our hair. As we are standing on an insulated material, the charges cannot get to the ground. We are filled up with electrons. Even our hair is filled up with electrons and becomes negatively charged. Like charges repel. Hence the strands of hair which are negatively charged repel each other and stand.

Video on Acids and Bases

What is the PH scale? Learn about acids and bases. Find out how they are measured and classified.

Click on the Heading to view the movie. At the end of the short movie, you can take an interactive quiz to see what you've learned.