Help in chemistry over thermodynamics and gases?

Question

I have a test monday and i'm lost we are in the gas chapter and thermodynamic chapter. Could someone explain what the molecular velocities and grahams law of effusion is? What is the root-mean-square velocity of gas particles? What in the h*** is enthalpy, change in enthalpy, Hess's law, and calorimetry and how does it relate to chemical equations? My teacher is Russian and she has a strong accents o I dont understand what she is saying and the books is evem more difficult to understand with all thise different triangles and letter and stuff...i've even bought 2 different chemistry books outside of my text book and they both explain the gas and thermochemistry chapters very confusing, I just feel like giving up some1 please help. Eveytime i ask someone to help me they claim they have a paper to write or something to do that is more important than the test.

Answer 1

i wil work with you. i like talking about things i can understand. you can add me to your contact list and i will add you to mine. molecular velocity is the speed of a molecule of gas in a tank. the point that they will eventually get to is that temperature is a result of molecular velocity. they will show you an equation that has T=f(v). this means temperature is caused by velocity. more velocity, higher temp.
ask a problem out of the chapter on molecular velocity and i will answer it then we can move to the next topic. one at a time, ok? effusion rate is the speed at which molecues of gas will excape from a tank if the tank have a small pin hole poked into it. if its two gasses in that tank and each gas has a different molecular weight, its the gas with the smallest weight that will come out of the tank the fastest. read this link real good about effusion. http://en.wikipedia.org/wiki/Graham%27s_law

Answer 2

Graham's Law:

http://dbhs.wvusd.k12.ca.us/webdocs/GasLaw/Gas-Graham.html

Thermochem, enthalpy, Hess:

http://dbhs.wvusd.k12.ca.us/webdocs/Thermochem/Thermochem.html

enthalpy: The change in enthalpy of the system is the heat transferred from surroundings to system in a constant pressure process.

constant pressure means a container open to the atmosphere, the styrofoam cups used in introductory classes. The amount of enthalpy in a given substance CANNOT be measured, but the change in enthalpy during a chemical reaction can.

These changes have been codified and tabulated. Certain conditions are specified (standard conditions) and the concept of a formation reaction has been developed. So, we have have the term "standard enthalpy of formation."

We can add two or more reactions together to get another reaction. Hess' Law is useful because the enthapies of the added reactions can also be added together to get the enthalpy of the target reaction.

RMS velocity. The average velocity of all gas particles in a gas sample is zero. This is because velocity is a vector quantity, incorporating both speed and direction. This means some velocities are in a positive direction and some in a negative direction, leading to the average of zero.

Take all individual velocities, square them, average the squares, then take the square root. That is a non-zero value called root mean square.

Best wishes on your test. It will be a work-filled weekend for you, but it could be a lot, lot worse. You could be a Republican facing re-election in 2008.

Answer 3

The help you need is much greater than anyone on here can provide you. From your question, it seems you've been lost longer than just very recently. You need to find a tutor who can work with you, and you'll obviously need to spend many many hours over the next few days to be at all ready for this test. I don't think you can blame your lack of understanding on your teacher's accent, but on your failure to keep up with the material. At the very first instant that you felt lost, you should have sought out help. As far as other people not being willing to help you, my gut feeling is that by waiting until the last minute to realize you need help, you've very much brought this on yourself. As a professor, I have very little sympathy for a student who comes to me two days before an exam and says "I don't understand anything you've talked about for the last three weeks. Can you re-teach me everything you've done in the next 15 minutes?" Your learning can't happen that way.

Good luck, but you won't get a lot of sympathy from me. If you should have a few specific questions and points of confusion, I'll be happy to help you understand them...multiple chapters of total lack of understanding is too much to help with here...

Answer 4

what the previous guy reported and that as quickly as gas touches your physique, the warmth from the gas transfers to you physique, that's at a decrease temperature. while the gas is going to a decrease temp when you consider which you physique takes warmth means from the gas, its temperature is decreased. by way of fact it won't be able to sustain its a hundred levels C, it fairly is going to become a liquid. i could say that the burn is led to when you consider which you physique won't be able to soak up all the warmth at as quickly as and is crushed with it so there's a unfavourable result (burns)