Archives of Ask A Scientist!
About "Ask A Scientist!"
On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.
Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.
There are three molecules involved in your explosion: hydrogen and oxygen, and the product, water. The hydrogen molecule is made up of two atoms of hydrogen (written as H2), the oxygen molecule is made up of two atoms of oxygen (O2), and water is made up of two atoms of hydrogen plus one atom of oxygen (H2O). Atoms are made up of a tiny positively charged nucleus surrounded by a cloud of negatively charged electrons. Sometimes when atoms come together they can reach a lower energy state by sharing their electrons. These shared electrons that spend their time in between two nuclei act as a glue to hold to nuclei together, and that's how you get molecules. These shared electrons are called chemical bonds. In H2 you have two electrons that are shared between the two hydrogen nuclei; this is counted as one bond. Some bonds are stronger than others. For example, in O2 you also have a bond, but the bond is stronger than in H2. In H2O you have two bonds, one from each hydrogen to the oxygen atom.
If you add up the energy it takes to break the bonds in H2 and O2, and subtract the energy it takes to form the bonds in H2O, you find that there is energy left over. (You have to do the math carefully. To conserve atoms, you must have 2 H2's combining with 1 O2 to give 2 H2O. So you are breaking two H-H bonds and one O-O bond, and making four H-0 bonds). The "left over" bonding energy in this chemical reaction gets turned into the light, heat, and sound that we call an explosion. In a car, there is bonding energy left over when the gasoline molecules combine with oxygen in the air to make carbon dioxide and hydrogen, and we use that energy to move the pistons and make the car move. Many chemical reactions give off heat, only to a lesser degree. Put your hand into a pile of decaying leaves next fall and you'll find that it's warm. Some reactions even take up energy and feel cold, although these are less common. Amazingly, in some chemical reactions, like the reactions going on inside firefly's tails that glow in the dark, the excess bonding energy is converted almost completely into light instead of heat.
- Why is vegetable oil able to be used as a power source for automobiles?
- I have heard of ways to get energy through the braking of a car. How does this work?
- What are hydrothermal vents?
- What is the smallest amount of a substance that can still have color?
- I've heard that due to the massive amount of empty space in and between atoms, people could walk through a brick wall. How true is this from a scientific point of view?
- If you take a substance like water and were able to get it to absolute zero, where supposedly the molecules would cease to move, and then you reheated it, would the molecules recover and start to move again?
- Why do baseball bats sting you when you hit a baseball?
- Why do crystal glasses give off sound when you rub them with a wet finger?
- What is a Green Flash?
- What are MEMS and why are they an important scientific break through?