EFellows28 My Chemistry

Last quiz...

I don't think that I did so well on the Gas Laws quiz. I know that for the test, I'll need to study the different laws closer, and notice the differences between them. I missed a day, and totally had no clue what STP was, which seems pretty important now.

STP

Air Bag Lab

We had to construct an air bag... one that would save our passenger's life but also not hurt the passenger from being too full of air.
Here's what we decided to do...

Find maximum volume of the bag

Fill bag with water
pour H2O into a graduated cylinder--- Volume H2O=Volume CO2

Calculate to determine amount of NaHCO3 needed

Volume from step 1, convert to L
Looking for NaHCO3... n=PV/RT
solve for moles of CO2
use stoich to find grams of NaHCO3
Baking soda=vinegar 1:1 molar ratio
Use D of vinegar to find volume of vinegar
x.20 because vinegar is only 5% acetic acid

Multiply measurements by .65 to not completely fill up the bag (or explode it)

http://www.chemistry.wustl.edu/~edudev/LabTutorials/Airbags/airbags.html

http://chemistry.about.com/od/chemicalreactions/f/What-Is-The-Equation-For-The-Reaction-Between-Baking-Soda-And-Vinegar.htm

PVNRT

PV=nRT
R=universal gas constant .0821 L atm/ mol K

EX. Calculate the pressure in atm exerted by 1.82 mol of Sulfur Hexaflourine gas in a steel vessel with a volume of 5.43 L at 69.5 degrees C (+273.15)

PV=nRT
P= nRT/V

(1.82 x .0821 x 342.65)/ 5.43
=9.43 atm
http://www.phscale.net/idealgaslaw.htm
http://www.westfield.ma.edu/cmasi/gen_chem1/Gases/ideal%20gas%20law/pvnrt.htm

Measuring Pressure

Common units of pressure:

Pascal Pa

Avg Air pressure at sea level 101,325

Kilopascal kPa

Avg Air pressure at sea level 101.325

Atmosphere atm

1 exactly

Millimeters of Mercury mmHg

760 exactly

Inches of Mercury inHg

29.92

Torr torr

760 exactly

Pounds per square inch psi

14.7

CONVERT 688 mmHg to atm
688mmHg x (1atm/760mmHg) = .905 atm

http://www.sengpielaudio.com/ConvPress.htm

Boyle's Law

TELLS THE RELATIONSHIP BETWEEN PRESSURE AND VOLUME IN AN INVERSE RELATIONSHIP

P1V1=P2V2

Ideal gas at low pressure holds strictly to this relationship

http://www.wisegeek.org/what-is-boyles-law.htm

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/gases-5/gas-laws-51/boyle-s-law-volume-and-pressure-254-8360/

Calculating Heat...

Q=MCΔT

Q= Heat in Joules
M= Mass in grams
C= Specific Heat
ΔT= Change in Temperature

EXAMPLE:
Calculate the amount of energy in joules required to heat 454 grams of water from 5.4 degrees C to 98.6 degrees C. Calculate the amount of energy in calories, too.
Q=?
M=454 g
Tinitial=5.4 degrees C
Tfinal=98.6 degrees C
c= 4.184 J/gdegC
Q=454x4.184x(98.6-5.4)
Q=1.77x10^5 Joules or 177 KJ

https://www.youtube.com/watch?v=4RkDJDDnIss
http://www.wikihow.com/Calculate-Specific-Heat
http://chemistry.about.com/od/workedchemistryproblems/a/Specific-Heat-Example-Problem.htm