Test Ch.10

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

____	1.	What conditions are referred to as standard temperature and pressure (STP) for gas behavior?
a.	0°C and 1 atm	
b.	0°C and 1 mm Hg	
c.	273°C and 1 atm	
d.	25°C and 1 atm	
e.	298 K and 760 torr	

____	2.	How are the pressure and the absolute temperature of a gas related for a given number of moles at constant volume?
a.	They are exactly opposites.	
b.	They are not related.	
c.	They are directly proportional.	
d.	They are indirectly proportional.	
e.	Not enough information given to determine.	

____	3.	Which of the following is not a postulate of the kinetic-molecular theory of gases?
a.	All gases consist of atoms and molecules moving randomly in all directions at various speeds.	
b.	The average kinetic energy of gas molecules increases as the temperature increases.	
c.	The volume of a gas molecule is negligible when compared to the space that separates it from other gas molecules.	
d.	Gas molecules will eventually stop colliding due to the energy lost in each collision.	
e.	There are no attractive or repulsive forces between gas molecules.	

____	4.	Based on temperature, there are four main layers to our atmosphere. Which of the following is the correct name for the layer in which we live?
a.	troposphere	
b.	thermosphere	
c.	stratosphere	
d.	mesosphere	
e.	ionosphere	

____	5.	Arrange the following gaseous substances in order of decreasing average molecular speed at 25°C.
argon, fluorine, carbon dioxide, oxygen, helium
a.	helium > oxygen > fluorine > carbon dioxide > argon	
b.	helium > oxygen > fluorine > argon > carbon dioxide	
c.	argon > oxygen > helium > carbon dioxide > fluorine	
d.	carbon dioxide > argon > fluorine > oxygen > helium	
e.	carbon dioxide > fluorine > argon > oxygen > helium	

____	6.	When the external pressure on a balloon is decreased at constant temperature, what happens to the gas inside?
a.	The collisions become more elastic.	
b.	The gas undergoes no changes.	
c.	The volume increases.	
d.	The molecules increase in rate of movement.	
e.	The volume decreases.	

____	7.	Which of the following is a mathematical representation of Charles's Law?
a.	P/T = constant	
b.	PV = constant	
c.	V ´ T = constant	
d.	n ´ T = constant	
e.	V/T = constant	

____	8.	If, at constant pressure, the absolute temperature of a flask equipped with a moveable piston is reduced to half its original absolute temperature, what must be the new volume?
a.	1/4 the original volume	
b.	1/2 the original volume	
c.	two times the original volume	
d.	four times the original volume	
e.	equal to the original volume	

____	9.	A "free radical" is which of the following?
a.	formed from the combination of two photons	
b.	a negatively charged species	
c.	a species that exists only in theory, not in reality	
d.	an atom or a molecule containing an unpaired electron	
e.	very stable and unreactive	

____	10.	What net product results from the reaction of ozone with CFCs?
a.	water	
b.	hydrogen	
c.	oxygen molecules	
d.	chlorine molecules	
e.	oxygen radicals	

Short Answer

	11.	A mixture of H2(g) and Cl2(g) exerts a total pressure of 2.50 atm. If the mole fraction of H2 is 0.250, what is the partial pressure (in atm) of H2?  Gas Law:_____________

	12.	At 20.0°C, a sample of gas has a volume of 2.51 L at 780 torr. What is the new pressure (in atm) if the volume is increased to 6.43 L at the same temperature? Gas Law:__________

	13.	The volume of a gas in a flask is 250.0 mL at 23°C and 1.00 atm of pressure. The gas is transferred to a new flask with a volume of 1.200 L at the same pressure. Under these new conditions, what is the temperature (in °C) of the gas?   Gas Law:__________

	14.	What is the density of chlorine gas (O2) at STP?    Gas Law:________

	15.	What volume (in L) of oxygen at 298K and 1.50 atm is required for the complete combustion of 15.0 g of hexane? The value of R = 0.0821 L atm mol-1 K-1.     Gas Law:___________
	2 C6H14 + 19 O2 ® 12 CO2 + 14 H2O

	16.	Calculate the number of moles of a gas that occupy 5.3 ´ 103 mL at STP. The value of R = 0.0821 L atm mol-1 K-1.  Gas Law:____________

	17.	If 5.63 g of an unknown gas occupies 79.1 mL at 25.02°C and 7.00 atm of pressure, what is the molecular weight of that gas? The value of R = 0.0821 L atm mol-1 K-1.  Gas Law: __________________

	18.	A gas occupies 10.0L at STP.  Calculate the new pressure of the gas if the temperature rises to 65.2°C and volume and mols are held constant.  Gas Law:________________

	19.	Suppose that at STP a gas occupies 10.2L.  At what temperature will the same gas occupy 1.50 mL at 1550.5 Torr.   Gas Law:________

	20.	Nitrogen and oxygen gas react to form ammonia gas in the reaction
	N2(g)  +  3H2 (g)  -->  2 NH3 (g)

If 250.ml N2 at 1.0 atm and 25.0°C were available for the reaction, what volume of H2 at the same temperature and pressure, would be required in the reaction?  Gas Law:_________

Test Ch.10
Answer Section

MULTIPLE CHOICE

	1.	ANS:	A	OBJ:	10.5 The Ideal Gas Law

	2.	ANS:	C	OBJ:	10.5 The Ideal Gas Law

	3.	ANS:	D	OBJ:	10.3 Kinetic-Molecular Theory

	4.	ANS:	A	OBJ:	10.1 The Atmosphere	

	5.	ANS:	B	OBJ:	10.3 Kinetic-Molecular Theory

	6.	ANS:	C	OBJ:	10.4 The Behavior of Ideal Gases

	7.	ANS:	E	OBJ:	10.5 The Ideal Gas Law

	8.	ANS:	B	OBJ:	10.5 The Ideal Gas Law

	9.	ANS:	D	OBJ:	10.10 Chemical Reactions in the Atmosphere

	10.	ANS:	C	OBJ:	10.11 Ozone and Ozone Depletion

SHORT ANSWER

	11.	ANS:	
1.23

OBJ:	10.8 Gas Mixtures and Partial Pressures	

	12.	ANS:	
0.406

OBJ:	10.5 The Ideal Gas Law

	13.	ANS:	
1.148 ´ 103

OBJ:	10.5 The Ideal Gas Law

	14.	ANS:	
1.43 g/L

OBJ:	10.5 The Ideal Gas Law

	15.	ANS:	
45.0

OBJ:	10.6 The Quantities of Gases in Chemical Reactions

	16.	ANS:	
0.33

OBJ:	10.5 The Ideal Gas Law

	17.	ANS:	
312

OBJ:	10.7 Gas Density and Molar Masses		

	18.	ANS:	
pressure

	19.	ANS:	
temperture

	20.	ANS:	
1.5L