In the last week and a half we learned
differences between physical and chemical changes. We performed
experiments where we either burned a substance or combined two substances
together. From what I saw in our
experiments I would say that chemical changes occur when a new substance is
produced and physical changes occur when the substance stays the same and there
is no molecular change to the substance.
Some properties of a chemical change would be a new substance is
produced, heat is produced, or there is a color change. An example of a chemical change from our lab
was when we put the piece of magnesium metal into a flame and light and heat
were produced. Afterwards the magnesium
had turned into a difference ash like substance. An example of a physical change from our lab
is when we put the wire test rod into a flame.
The wire did get red hot but it stayed the same substance meaning it was
a physical change. We also learned about
mass of substances when they are burned or combined with other substances. If the mass of two substances stayed the same
when they were combined then there was no interaction between them and it was
just a mixture. When we performed the
experiment where measured the mass of steel wool, burnt it, then measured again
the mass became greater because more air was added to it. When we did the experiment where we just
pulled the steel wool apart the mass decreased very little.
