1.

Represented above are five identical balloons, each filled to the same volume at 25°C and 1.0 atmosphere pressure with the pure gas indicated.(a) Which balloon contains the greatest mass of gas? Explain.(b) Compare the average kinetic energies of the gas molecules in the balloons. Explain.(c) Which balloon contains the gas that would be expected to deviate most from the behavior of an ideal gas? Explain.(d) Twelve hours after being filled, all the balloons have decreased in size. Predict which balloon will be the smallest. Explain your reasoning

(a) two pointsCO2

because all contain same number of molecules (moles), and CO2 molecules are the heaviestNote: total of 1 point earned if CO2 not chosen but same number of molecules (moles) is specified

(b) two pointsAll are equalbecause same temperature, therefore same average kinetic energyNote: just restatement of "same conditions, etc." does not earn second point

(c) two pointsCO2

either one:

it has the most electrons, hence is the most polarizableit has the strongest intermolecular (London) forces

Note: also allowable are "polar bonds", "inelastic collisions"; claiming larger size or larger molecular volume does not earn second point

(d) two pointsHeAny one:

greatest movement through the balloon wallsmallest sizegreatest molecular speedmost rapid effusion (Graham's law)

2. How many moles of an ideal gas at 138.85oC does it take to fill a 19 m3 container at a pressure of 1.459 x 10 5 Pa ?

809, 8 moles

3) You decide to go on a long hot air balloon ride, so you decide to bring some shampoo towash your hair with. However there is some gas inside the shampoo bottle when youstart to climb into the basket at the beginning of your journey. In fact, because you are agood scientist you decide to constantly take measurements of your surroundings. Theshampoo bottle contains 435ml of gas, under a pressure of 1.10 atm, at a temperature of30.0°C. When you climb high into the air the bottle starts to expand eventuallyexploding and covering you and your companions with Pert Plus. Eager to explain thisphenomenon you take some measurements: the pressure, you note, has dropped to0.734 atm and the temperature has dropped to 5.00°C.

To what new volume did the gas inside the bottle expand?

) 598 mL

4. The Hindenburg was a famous hydrogen-filled dirigible that exploded in 1937. If the Hindenburg

held 2.0 x 105 m3 of hydrogen gas at 23oC and 1.0 atm, what mass of hydrogen was present?

5. Chlorine is widely used to purify municipal water supplies and to treat swimming pool waters.

Suppose that the volume of a particular sample of Cl2 is 8.73 L at 755 torr and 24oC.

a. How many grams of Cl2 are in the sample?

b. What volume will the Cl2 occupy at STP?

6. In an experiment reported in the scientific literature, male cockroaches were made to run at different speeds on a miniature treadmill while their oxygen consumption was measured. In one hour the average cockroach running at

0.08 km/hr consumed 0.8 mL of O2 at 1 atm pressure and 24oC per gram of insect weight.

a. How many moles of O2 would be consumed in 1 hour by a 5.2 g cockroach moving at this

speed?

b. This same cockroach is caught by a child and placed in a 1-quart fruit jar with a tight lid. Assuming the same level of continuous activity as in the research, will the cockroach consume more than 20 percent of the available O2 in a 48-hour period? (Air is 21 mol

percent O2.)

7. Cierto gas tiene una densidad de 3,17 g·dm−3 en condiciones normales La masa molar de dicho gas es:a) 38,65 g·mol−1 b) 71 g·mol−1 c) 7 g·mol−1 d) 86,12 g·mol−1

Sabiendo que le volumen molar de un gas en condiciones normales es 22,4 L

8. ¿Cuál será la presión total en el interior de un recipiente de 2 L que contiene 1 g de He,14 g de CO y 10 g de NO a 27°C?a) 21,61 atm b) 13,33 atm c) 1,24 atm d) 0,31 atm

9. Dos moles de distintos gases, en igualdad de condiciones de presión y temperatura,tienen: a) La misma masa. b) El mismo número de átomos.c) La misma energía interna. d) El mismo volumen.

10.Considerando el aire como una mezcla homogénea de composición volumétrica 78% denitrógeno, 21% de oxígeno y 1 % de argón, la “masa molar aparente” del aire resulta ser:a) 14,68 g/molb) 28,96 g/mol c) 29,36 g/mol d) No se puede conocer.

11. Una muestra de Kr (g) se escapa a través de un pequeño agujero en 87,3 s y un gasdesconocido, en condiciones idénticas, necesita 42,9 s. ¿Cuál es la masa molar del gasdesconocido?a) 40,5 g/mol b) 23,4 g/mol c) 20,2 g/mol d) 10,5 g/mol

12. Se dispone de una mezcla de 150 g de N2 (g) y 150 g de H2 (g) para iniciar la síntesis deamoníaco. Si la presión total de la mezcla gaseosa es de 1,5 atm, la presión parcial de N2 (g)es:a) 0,10 atm b) 0,25 atm c) 1 atm d) 1,25 atme) 0,75 atm

13. Un recipiente contiene a 130°C y 760 mmHg, 50 g de cada uno de los siguientes gases:CO2, O2, Ne, N2 y H2O. Las velocidades moleculares medias son:a) CO2 > Ne > N2 > H2O < O2

b) O2 > Ne > CO2 > N2 > H2O

c) CO2 = Ne = N2 = H2O = O2

d) H2O > Ne > N2 > O2 > CO2

Qué sucedería con la presión de un gas si sus moléculas permanecieran estáticas?a) Aumentaría la presión.b) Seguiría igual la presión.c) Descendería la presión.d) Sería nula la presión.

15 volume 0 ¿ not posible

16. 25.0 mL of Carbon dioxide gas is collected by water displacement in a gas collecting tube. The water level inside the collecting tube is 58 mm above the level of the outside water. The temperature of the system is 27oC and the barometric pressure outside is 777 mmHg. What would be the volume of just the carbon dioxide gas (the Dry Gas) if the conditions are changed to STP? (at 27oC the water vapor pressure = 26.739 mmHg) a) answer ________________8) 22.3 or 22.4 mL , Dalton’s and Combined Gas laws b) what 2 laws are used to solve this problem? _______________ & ______________________

2. An open-end manometer possesses a 20.4L reactionchamber. The complete combustion of a certainquantity of propane gas produces 13.203g of CO2 gasand 7.2064g of water vapor. If the temperature of thechamber is 353.15K and the equilibrium mercury levelis 11mm higher on the reaction side of the chamber,what is the atmospheric pressure in torr?

20. How many liters of H2(g) measured at STP are formed from the complete reaction of 1.31 g of magnesium with hydrochloric acid? The reaction is

Mg(s) + 2HCl(aq) →H2(g) + MgCl2(aq)

How to calculate molecular formula from density?determine the molecular formula of a substance that contains 92.3%C and 7.7%H by mass. This same substance when in the gas phase has a density of 0.00454g/ml at stp conditionsassume 100 grams

carbon = 92.3 grams x ( 1 mole / 12.0 g) = 7.69 moleshydrogen = 7.7 grams x (1 mole / 1.0 g) = 7.70 moles

divide by the smaller and you find the empirical formula to be

CH and CH has mass of 13.0 g / mole CH

next... assume you have an ideal gas...

PV = nRT n = mass / mw PV = (mass / mw) RT

mw = mass RT / PV = (mass / V) x RT/P = ρ x RT/P

mw = (.00454 g/ml x (1000 ml / L)) x (.0821 Latm/moleK) x (273.15K) / (1 atm)

mw = 101.8 g / mole

so molecular formula = (101.8 g / mole unknown molecule) x ( mole CH / 13.0g) =

= 7.83 CH's per molecule....

are you sure about those numbers? if the density was 0.00464, instead of 0.00454, then.....mw = 104.1 and your molecular formula would be C8H8