BIOPHYSICAL SCIENCE review session UNIT 9 GASES

1.When the gas exerts pressure, gas particles collide with the walls of the container. Gas units are atmosphere ( ), millimeter of mercury ( ), kilopascal ( ). atm mmHg kPa

2.Gases have ____________ shape and ___________ volume. When you compress gases, you can ________ly compress. indefinite easi

3.STP is an abbreviation of _______ ____________ and _________ when gases are at ___ atm and ____ o C. Standard temperature pressure 1 0

4)List the assumptions of the kinetic molecular theory of gases a)Motion → constant, random, linear motion b)Collision → elastic collision c)volume of gas particle. → negligible (almost 0)

5) Gas laws and relationship Constant Variable n and T n and Pn and Vn Variable under study P and V V and TP and TP,V,T Name of Law Boyle’s Law Charles’ law Gay- Lussac Combined gas law Inversely or Directly proportional Inversely proportional Directly proportion al Equation P 1 V 1 =P 2 V 2 V 1 = V 2 T 1 T 2 P 1 = P 2 T 1 T 2 P 1 V 1 = P 2 V 2 T 1 T 2

6)Combined gas law → P 1 V 1 = P 2 V 2 T 1 T 2 7)Ideal gas law  PV=nRT

8)What is the letter “R” in the equation of ideal gas law? → R is universal gas constant

9)What happens to the pressure of a sample of gas in the syringe if its volume is increased from 5.0 mL to 20.0 mL? → Volume is increased 4times (quadruple), so pressure will be decreased ¼

10)A sample of gas occupies 24 L at 175 o C. What volume would the gas occupy at 400.0K? V1 = 24LT1= =448K V2= ?T2=400.0K 24L = V 2 448K 400.0K V 2 =21L

11)The gas in a balloon has a volume of 7.5 L at 100. kPa. The balloon is released into the atmosphere, and the gas in it expands to a volume of 11L. Assuming a constant temperature, what is the pressure on the balloon at the new volume? P1=100.kPaP2=? V1= 7.5LV2=11L (100kPa)(7.5L) = P2(11L) (Boyle’s law) P2 = 68kPa

12)The gas in a sealed can is at a pressure of 3.00 atm at 25 o C. A warning on the can tells the user not to store the can in a place where the temperature will exceed 52 o C. What would the gas pressure in the can be at 52 o C? P1=3.00atmP2=? T1=25 o C + 273K=298K T2=52 o C +273K=325K 3.00atm = P2. 298K 325K P2=3.3atm

13)How do you realize the methane gas is leaking from the gasket? Methane gas particles collide with other particles, walls and floors randomly. So, you can smell it after several seconds.

14)Gas in a balloon occupies 2.5 L at 27 o C. The balloon is dipped into liquid nitrogen that is at a temperature of 80.0K. What volume will the gas in the balloon occupy at this temperature? V1=2.5LV2=? T1=27 o C + 273K=300KT2=80.0K 2.5L = V2. 300K 80.0K V2=0.67L

15)Which travel faster, oxygen molecules (O 2 ) or sulfur trioxide molecules (SO 3 ), assuming that they both are at the same temperature? Compare both gas’ molar mass O 2 =32.00g/mol, SO 3 =80.07g/mol Since smaller or lighter particles move faster, oxygen molecules travel faster than sulfur trioxide.

16)A mixture of gases is under a pressure of 1.0 atm. The mixture contains atm of helium and atm of oxygen and unknown pressure of nitrogen gas. Calculate the partial pressure of nitrogen gas. Total pressure is same as sum of partial pressure 0.450atm atm + x = 1.0 atm X= 0.30 atm Nitrogen gas = 0.30 atm

17)A weather balloon containing helium with a volume of L rises in the atmosphere and is cooled from 27 o C to - 27 o C. The pressure on the gas is reduced from kPa to 25.0 kPa. What is the volume of the gas at the higher altitude? P1=110.0kPaP2=25.0kPa V1=410.0LV2=? T1=27 o C+273K=300K T2=-7 o C+273K=246K 110.0kPa x 410.0L = 25.0kPa x V2 300K 246K V2=1500L

18) The following combustion reaction occurs in the automobile engine. 2 C 8 H 18 (l) + 25 O 2  16 CO 2 (g) + 18 H 2 O (g) a) How many liter of octane (C 8 H 18 ) are there if there are 1.50 mole of octane at 300. K and 1.25 atm? Only one number for each variable Mole is given  ideal gas law P=1.25atmV=? n=1.50mol T=300.K (1.25atm)(V)=(1.50mol)( )(300.K) V=29.5L

2 C 8 H 18 (l) + 25 O 2  16 CO 2 (g) + 18 H 2 O (g) b) How many moles of oxygen gas did you use of this reaction at same temperature and pressure? How many substances?  2 subs  stoich V=29.5L (Use previous info) 29.5L C 8 H 18 x 25mol O 2 2 mol C 8 H 18 = 369 L O 2

19) Explain the following using gas laws. a) Aerosol cans will explode when heated. Higher temperature, increase volume (Charles’ law)

19) Explain the following using gas laws. b) A coke can with hot water will collapse when it would be put in cold water upside down. Inside the can is high temperature. Once it is put in cold water upside down, the air can’t get in and the temperature decreases. Lower temperature, decrease volume or pressure. (Either Charles’ law or Gay-Lussac’s law)

19) Explain the following using gas laws. c) Tire pressures should be measured when they are cooled rather than when they are hot. With high temperature, the tire pressure is high. With low temperature, the tire pressure is low. If the pressure was measured at high temperature, the tire pressure will be lower. Low tire pressure causes flat tire. (Gay-Lussac’s law)

19) Explain the following using gas laws. d) If you release a helium balloon, it soars upward and eventually pops. High elevation is low pressure. Low pressure increase volume, therefore balloon pops. (Boyle’s law)

19) Explain the following using gas laws. e) When you come back to lower altitude, the sealed plastic bottle with air from high altitude will collapse. High altitude is lower atmospheric pressure. When you come back to lower altitude, pressure increases. Higher pressure, lower volume of bottle. (Boyle’s law)

20) When the vapor pressure became same as atmospheric pressure, it is called boiling. When you boil water at high altitude, the boiling point will be lower than sea level.

21) Phase diagram of water a)Triple point Three phases are present at the same time. b)What is the pressure when water boils? 1.0 atm c)What term is used to explain the process when ice changes to water? Melting

22) Heating curve of water a.Which letter represents the existence between liquid and gas? D b.What phase of matter is represented by letter C? liquid

22) Heating curve of water c. What phase change occurs as heat is removed from letter B? freezing