Construction of an Air Bag Lab

So our only lab this unit (I think) is the construction of an air bag lab.

 Basically, we have to figure out how to inflate a plastic bag (size unknown) enough to where it can be pinched in but not enough to where it blows up.

We are utilizing vinegar and baking soda to produce the gas.

To figure out this amount of gas, we need to use stoichiometry and gas laws.

Here are some links is you need help with that:

https://socratic.org/questions/how-do-you-solve-a-gas-law-stoichiometry-problem

http://www.science.uwaterloo.ca/~cchieh/cact/c120/gastoichiometry.html

http://people.uwplatt.edu/~sundin/114/l114-17.htm

Reflection on the Quiz

Yesterday we took a quiz in class, and I don't think it went very well at all.

I am gong to make a post reviewing all of the stuff that was on the quiz that I did not know so that I know it for the test.

The first thing that was covered a lot was the kinetic theory of gases. The postulates are:

• Gases consist of small particles (molecules) that are in continuous, random motion.
• The volume of the molecules present is negligible compared to the total volume occupied by the gas. 
• Intermolecular forces are negligible.
• Pressure is due to the gas molecules colliding with the walls of the container. 

The rest of the questions that stumped me were mostly just logic and conceptual, so I can't really post anything that would help with that.

Hopefully your quiz went better than mine!

Avagadro's and the Combined Gas Law

Avogadro's Law tells us for that a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas present.

Equal volumes of gas at the same temp and pressure will  have the same number of particles.

This holds true for gases at low pressures.

The mathematical formula for this law is V1n2=V2n1

*The volume of 1 mol of gas at STP (0 C or 273.15 K) is 22.4L.

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The combined gas law is the only law with 6 variables.

This is a combined formula of all the gas laws when all variables change.

The mathematical formula for this one is P1V1T2=P2V2T1

Here are some links if you need more help:

http://www.chemteam.info/GasLaw/Gas-Avogadro.html

http://www.chemistry.co.nz/avogadro.htm

http://www.chemteam.info/GasLaw/Gas-Combined.html

Charles' Law

The next law we learned about is Charles' Law

This law tells us that temperature and volume vary directly with each other at a constant pressure.

The temperature for this law must be in Kelvins, but to convert C to K all you have to do is add 273.15.

As temperature increases, the gas wants to expand, and since pressure is constant, it can only increase in volume.

The mathematical formula for this is V1T2=V2T1

Absolute zero, or where there is no kinetic movement at all, is -273.15 C.

Boyle's Law

Today we learned about the first gas law, Boyle's law.

It tells us that the relationship between pressure and volume is inverse.

It holds a constant temperature and only deals with pressure and volume. 

But, the only gas that holds strictly to this relationship is an ideal gas at low pressures.

The mathematical formula for this law is P1V1 = P2V2

Intermolecular Forces

Intermolecular forces are forces of repulsion or attraction between neighboring molecules. They are weak compared to the intramolecular forces, the forces which keep a molecule together.

Weakest to strongest, they are London dispersion, dipole dipole, hydrogen, & ionic bonding.

Here is a simple picture illustrating how to determine which type of bonding is present.

Another thing to remember is that stronger intermolecular forces result in higher boiling points, seeing as the bonds require more heat to be broken due to their strength. 

Here are some links I found helpful:

http://chemistry.bd.psu.edu/jircitano/IMforces.html

http://www.chem.ucla.edu/~harding/notes/notes_14C_noncoval02.pdf\

Heating Curve and Phase Diagrams

In this unit there are two main graph/image based pieces of information: heating curves and phase shift diagrams.

Here is the heating curve. It is important to note that you calculate energy from A-B, C-D, and E-F by mc^T. B-C is mLf and D-E is mLv.

Here is the phase shift diagram. The first, top left section is solid, the central upper is liquid, and the lower right is gas. Point B is the critical temp and pressure and point A is the triple point, 

It is important to know how to read these graphs well in order to observe the behaviors of solids, liquids, and gases in different temperatures and pressures!

Here are some links so you can learn more: 

http://ch301.cm.utexas.edu/section2.php?target=thermo%2Fenthalpy%2Fheat-curves.html

http://www.kentchemistry.com/links/Matter/HeatingCurve.htm

http://study.com/academy/lesson/phase-changes-and-heating-curves.html