Chem Std.

11 b. Students know the energy release per gram of material is much larger in nuclear fusion or fission reactions than in chemical reactions. The change in mass (calculated by E = mc² ) is small but significant in nuclear reaction.


Albert Einstein is perhaps the most famous scientist of this century. One of his most well-known accomplishments is the formula
Despite its familiarity, many people don't really understand what it means. We hope this explanation will help!
Example:

= 0.111 x 300,000,000 x 300,000,000 = 10,000,000,000,000,000 Joules

This is an incredible amount of energy! A Joule is not a large unit of energy ... one Joule is about the energy released when you drop a textbook to the floor. But the amount of energy in 30 grams of hydrogen atoms is equivalent to burning hundreds of thousands of gallons of gasoline!


Two protons stuck together have less mass than two single separate protons!
When the protons are forced together, this extra mass is released ... as energy! Typically this amounts to about 0.7% of the total mass, converted to an amount of energy predictable using the formula .



Einstein's theories sprang from a ground of ideas prepared by decades of experiments. One of the most striking, in retrospect, was done in Cleveland, Ohio, by Albert Michelson and Edward Morley in 1887. Their apparatus, shown above, was a massive stone block with mirrors and crisscrossing light beams, giving an accurate measurement of any change in the velocity of light. Michelson and Morley expected to see their light beams shifted by the swift motion of the earth in space. To their surprise, they could not detect any change. It is debatable whether Einstein paid heed to this particular experiment, but his work provided an explanation of the unexpected result through a new analysis of space and time.