Gas+Laws

__**Directions:**__ a) list and define all vocabulary from the chapter b) type at least 4 sample problems with step-by-step directions of how to solve the problem; list the correct answers (if your chapter doesn't have math, there are still problems and concepts we learned.) c) link at least 3 websites for additional resources to help with studying d) develop your own LEQ questions for the section - what did you think were the key points we learned? e) Once your page is done, visit 4 other chapters and answer their LEQ's. (This can be done on a separate piece of paper.)

=__**Vocab-**__=

-units of pressure: - 1 atm- atmospheres = 760 mmHg = 760 Torr - 1 atm = 101,325 Pa (pascal) = 101.325 KPa (kilopascal)
 * Pressure- force / area
 * Boyle's Law- (P1)(V1) = (P2)(V2)
 * constant temperature, constant amount of gas
 * pressure changes inversely to volume
 * Charles' Law- V1/T1 = V2/T2
 * Temperature and volume increase proportionally
 * Temperature **MUST**be in Kelvin
 * T(k) = T(Celsius) + 273.15
 * Ideal Gas Law- PV= nRT
 * R is the gas constant - used when discussing a SINGLE gas in a NON-CHANGING environment
 * R = PV/ nT= (1 atm)(22.414 L) / (1 mol)(273.15 K)
 * R= (0.082057 x atm) / (mol x K) or (8.314 x KPa)/ (mol x K)
 * STP- Standard temperature and pressure= 0 degrees Celsius and 1 atm of pressure
 * Experiments show that at STP, 1 mol of an Ideal Gas occupies 22.414 L
 * Combined Gas Law- (P1)(V1) / T1 = (P2)(V2)/ T2
 * happens when n and R are constant
 * Dalton's Law of Partial Pressure = Ptotal= Pa+ Pb
 * V and T are CONSTANT
 * Pa = (nA)(R)(T) / V and Pb = (nB)(R)(T) / V
 * Mole Fraction (X) is the percent of each gas pressure present in the total.
 * XA= nA / (nA + nB) and XB= nB / (nA + nB)
 * Graham's Law= Rate 1 / Rate 2 = Sqr root of (M2 / M1)
 * Rate 1 = faster, lighter gas
 * Rate 2 = slower, heavier gas
 * Comparing two or more speeds of gases.

=**__Helpful LEQ's:__**=
 * When do you use each Gas Law?
 * What are the formulas of each gas law?
 * What are the units of pressure?
 * What are the different relationships between pressure and volume in the different gas laws?

=__**Practice Problems:**__=
 * Boyle's:
 * A sample of chlorine gas occupies a volume of 946 mL at a pressure of 726 mmHg. What is the pressure of the gas (in mmHg) if the volume is reduced at a constant temperature to 154 mL?
 * (726)(946)= P2(154)
 * Divide each side by 154 to find the figure for P2
 * the answer will be 4460 mL
 * Charles' :
 * A sample of carbon monoxide gas occupies 3.20 L at 125 degrees Celsius. At what temperature will the gas occupy a volume of 1.54 L if the pressure remains the same?
 * Change the temperature to kelvin: 125 + 273.15
 * T2 = V2(T1) / V1 = (1.54)(398.15) / 3.20 = 191.6 Kelvin
 * Ideal Gas Laws:
 * A Balloon contains 2.00 g of He at a pressure of 105 kPa and a temperature of 300 Kelvin. What is the volume of the balloon?
 * PV = nRT therefore V= (nRT) / P
 * Find the moles of He in 2.00 g
 * plug it all in
 * V= (.5)(300)(8.314) / 105
 * V= 11.9 L
 * Combined:
 * a 7.00L Sample of argon gas at 420 Kelvin exerts a pressure of 625 kPa. If the gas is compressed to 1.25 L and the temperature is lowered to 350 Kelvin, what will be the new pressure?
 * P1(V1) / T1 = P2(V2) / T2
 * 625(7.00L) / 420 K = P2(1.25) / 350 K
 * Cross multiply the fractions and solve for P2
 * P2= 2920 kPa
 * Dalton's:
 * A mixture of 1.00 g of H2 and 1.00 g of He is placed in a 1.00l container at 27 degrees C. calculate the partial pressure of each gas and the total pressure.
 * PV= nRT therefore P= nRT / V
 * Convert temp to Kelvin
 * Find the moles of H2, plug it all in:
 * (0.48)(0.0821)(300.15) / 1L = 12.07 atm H2
 * Do the same math for He:
 * (0.25)(0.0821)(300.15) / 1L = 6.16 atm He
 * Add the pressurestogether to get the Ptotal: 18.23 atm
 * Graham's Law:
 * What is the molecular weight of a gas which diffuses 1/50 as fast as hydrogen?
 * Rate1/ rate 2 = sqr root of M2 / M1
 * 1/50 = sqr root of 2.02 / x
 * Sqr both sides, cross multiply
 * X= 5050 g/mol

=Web Sites=
 * http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/gaslaws3.html
 * http://misterguch.brinkster.net/gaslaws.html
 * http://www.chm.davidson.edu/vce/gaslaws/index.html