Blog 2

We started off by filling the garbage bag with air.  We learned that while pushing air into the bag it would fill up and the air particles would bounce against the side of the bag making it inflate.  Next we did the mercury tube experiment. What we saw in that experiment was that the air pressure actually pushed the mercury up the tube.  If it's high pressure the mercury would be higher up the tube, if it's low pressure the mercury would be lower.  Then we saw how the air pressure pushed the petri dish to the top of the tank because there was no air between the water and the tank so the air pushed it against the tank.


We learned the units of pressure which are:    1 atm=760 mmHg
                                                                         101.3kPa=760 mmHg
                                                                         1 atm=101.3 kPa
The relationship between pressure and volume was that as volume goes down pressure goes up.  We saw that in the syringe because when we pushed it in volume went down and pressure went up and when we pulled it out volume went up and pressure went down.

Blog

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.