3/3/2015 week 2 Day1 Pressure, Volume, Temperature Relationships of ideal gas

the first experiment we did today is that put a litter water in a can and heat it, then put it into ice water.  The guess before the experiment and the reason and what would happen  is in the first photo: the can will be implode. The second to forth photos show us the process of the experiment and our guess is correct.

Then we don't add any thing in the can and heat the can, and doing another experiment and put the hot can in the ice water, we find that the can doesn't change to bigger or smaill, but when we take the can from the water we can see that there are many water is suctioned in the can. 

then we talked about the units of pressure and find the atmosphere that uses the equation on the right of the photo pgh is about 10^5 pa.

The next experiment is that we  put a balloon in an glass can and exhaust the air. we find that as the air loses in the can, the balloon become bigger. That is because when we exhaust the air, the pressure to the balloon in the can become smaller then the balloon can become bigger and bigger. 

then the next experiment we change the ballon to marshmallow and guess what happen. we think that marshmallow will shink when pulling air out and will return to original when release pressure. Then we start the experiment.

This video is the marshmallow'change.  when we put the air out the can, they are becoming bigger. when we release, they become smaller than original ,then we pumping air and they become bigger.

Then we start the experiment about the ideal gas. we use the equation pV=nRT to explored when one of pressure, volume and temperature doesn't change and change one of other two and find what will happen. 

There are three situations. First one, it is Boyles‘s Law, we keep T doesn't change and change the pressure of the air,  we find that V∝（1/p).Second one is Gay-Lussac‘s Law. we keep P doesn't change,  and put the air into ice water, nomal water and hot water and  find that V∝T. The last one is Charles’s Law. we keep Vdoesn't change, and find p∝T.

Then we do experiments by ourselves. we keep the temperature doesn't change and make volume from 6cc to 20cc and make the graph in the photo. we find that P*V is doesn't change. then we know that P*V=k(constant). the second photo is that we curve the line and find it slope.

then we make the graph of P and T (make the volume doesn't change) and find P/T =k（constant）and we curve the line to P=AT+B and find the unit of A is kpa/℃ and B is kpa.

Next, we make the graph of V and T(keep the pressure constant) and we find that V/T=k(constant). V=AT. and the unit of A is J/K.

Then we do some exercises about the equation PV=nRT and n=m/M

this exercise is that a diving bell in the deep water and find  the pressure. but we should notice that the pressure should add the atmosphere. 

this one is that we shuold find the height after we put the bell in the sea level. we should use P_i*V_i/T_i= P_f*V_f/T_f

this exercise is to find the mass of helium and we should use pv=nrt AND n=m/M

Conclusion:

Today in calss, we identify three different relationships in different experiments.. They are pressure, volume, and temperature.  We did three different experiments. The first one, we figure out that the pressure and volume had an inverse proportional relationship. The second one, we analyzed  the changes about temperature and volume  in constant pressure. The last experiment showed that the relationship about temperature and pressure when the volume is constant. These ideas based on Boyle's and Charles law. After the experiments, we know the equations of the ideal gas law where the three experiments were all in effect using Boltzmann's constant and the universal gas constant.