My Courses Chemistry: The Central Science, 12e Brown/LeMay ...€¦ · Signed in as Daniel Semenick , Instructor Help Sign Out Chapter 10 Quiz Due: 9:58pm on Thursday, October 30,

Signed in as Daniel Semenick , Instructor Help Sign Out

Chapter 10 QuizDue: 9:58pm on Thursday, October 30, 2014

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Go Figure 10.2Description: A mercury barometer. (a) What happens to h the height of the mercury column, if theatmospheric pressure increases?

A mercury barometer.

Chemistry: The Central Science, 12eBrown/LeMay/Bursten/Murphy/Woodward

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Chapter 10 Quiz [ Edit ]

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Part A

What happens to the height of the mercury column, if the atmospheric pressure increases?

ANSWER:

Chapter 10 Question 17 - Multiple ChoiceDescription: (a) Which one of the following is a valid statement of Avogadro's law?

Part A

Which one of the following is a valid statement of Avogadro's law?

ANSWER:

Problem 10.27Description: You have a gas confined to a cylinder with a movable piston. What would happen to the gaspressure inside the cylinder if you do the following? (a) Decrease the volume to one-fourth the originalvolume while holding the temperature constant. (b)...

You have a gas confined to a cylinder with a movable piston. What would happen to the gas pressure inside the

h

the height of the mercury column remains the same

the height of the mercury column increases

the height of the mercury column decreases

= constant

= constant

= constant

= constant

= constant

V !n

PV

PT

V !P

VT


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cylinder if you do the following?

Part A

Decrease the volume to one-fourth the original volume while holding the temperature constant.

ANSWER:

Part B

Reduce the temperature (in kelvins) to half its original value while holding the volume constant.

ANSWER:

Part C

Reduce the amount of gas to one-fourth while keeping the volume and temperature constant.

ANSWER:

= 4 "Pfinal Pinitial

Pfinal = Pinitial2

Pfinal = Pinitial4

Pfinal = 2 " Pinitial

Pfinal = Pinitial


=PfinalPinitial

2

=Pfinal Pinitial

=PfinalPinitial

4




=Pfinal Pinitial

=PfinalPinitial

4

=PfinalPinitial

2


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Problem 10.30Description: Nitrogen and hydrogen gases react to form ammonia gas as follows: N_2 (g) + 3H_2 (g)rightarrow 2(NH)_3 (g) At a certain temperature and pressure, V_1 of N_2 reacts with V_2 of H_2. (a) If allthe N_2 and H_2 are consumed, what volume of...

Nitrogen and hydrogen gases react to form ammonia gas as follows:

At a certain temperature and pressure, 1.1 of reacts with 3.3 of .

Part A

If all the and are consumed, what volume of , at the same temperature and pressure, will beproduced?

Express your answer using two significant figures.

ANSWER:

Chapter 10 Question 10 - BimodalDescription: (a) A sample of a gas originally at 25 °C and 1.00 atm pressure in a 2.5 L container is subjectto a pressure of 0.85 atm and a temperature of 15 °C. The final volume of the gas is __________ L.

Part A

A sample of a gas originally at 25 °C and 1.00 atm pressure in a 2.5 L container is subject to a pressure of0.85 atm and a temperature of 15 °C. The final volume of the gas is __________ L.

ANSWER:

± Changes in VolumeDescription: ± Includes Math Remediation. Calculate pressure given the change in volume at constanttemperature and molar amount. Calculate temperature given the change in volume at constant pressure and

(g) + 3 (g) # 2 (g)N2 H2 NH3L N2 L H2

N2 H2 NH3

= = 2.2 V L

2.8

0.38

2.6

2.1

3.0


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molar amount. Calculate new molar amount given the change in volume at constant temperature andpressure.

The ideal gas law ( ) describes the relationship among pressure , volume , temperature , andmolar amount . When some of these variables are constant, the ideal gas law can be rearranged in differentways to take the following forms where is a constant:

Name Expression Constant

Boyle's law and

Charles's law and

Avogadro's law and

Part A

A certain amount of chlorine gas was placed inside a cylinder with a movable piston at one end. The initialvolume was 3.00 and the initial pressure of chlorine was 1.50 . The piston was pushed down tochange the volume to 1.00 . Calculate the final pressure of the gas if the temperature and number ofmoles of chlorine remain constant..

Express your answer with the appropriateunits.

Hint 1. Identify the law that applies to the problem

Which gas law applies to this situation?

ANSWER:

Hint 2. How to set up the equation

In this problem, the volume is changing while the amount of gas and the temperature remain thesame. Since the product of pressure and volume is constant, we can set up the following equation

PV = nRT P V Tn

k

PV = nRT = k n T

= = kVT

nRP

n P

= = kVn

RTP

T P

L atmL

Boyle's law

Charles's law

Avogadro's law


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and solve it for :

ANSWER:

Boyle's law describes the inverse relationship between volume and pressure of an ideal gas. When thetemperature and amount of a gas remain fixed, an increase in volume results in a lower pressure, anda decrease in volume results in a higher pressure.

Part B

In an air-conditioned room at 19.0 , a spherical balloon had the diameter of 50.0 . When taken outsideon a hot summer day, the balloon expanded to 51.0 in diameter. What was the temperature outside indegrees Celsius? Assume that the balloon is a perfect sphere and that the pressure and number of moles ofair molecules remains the same.

Express your answer with the appropriate units.

Hint 1. How to approach the problem

The pressure and the amount of air inside the balloon remain the same. Therefore this is a Charles'slaw problem. We can set up the following equation and solve it for :

Start by calculating the initial and final volumes from the given diameters. Plug these values into theequation along with initial temperature in kelvins. Solve for the final temperature in kelvins and thenconvert it to degrees Celsius.

Hint 2. Calculate the initial volume of the balloon

The diameter of a spherical balloon is 50.0 . Calculate the volume of the balloon in liters.


Hint 1. Formula for volume of a sphere

The formula for the volume of a sphere is

where is the radius of the sphere and is the constant equal to 3.1416.

Hint 2. Conversion factor between cubic centimeters and liters

Pfinal

(PV = (PV)initial )final

= = 4.50Pfinal

C$ cmcm

Tfinal

( = (VT

)initial

VT

)final

cm

V = !43 r3

r !


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1 is equal to 1000 .

ANSWER:

Substitute this value for in the appropriate gas law equation.

Hint 3. Calculate the final volume of the balloon

The diameter of a spherical balloon is 51.0 . Calculate the volume of the balloon in liters.


Hint 1. Formula for volume of a sphere

The formula for the volume of a sphere is

where is the radius of the sphere and is the constant equal to 3.1416.

Hint 2. Conversion factor between cubic centimeters and liters

1 is equal to 1000 .

ANSWER:

Substitute this value for in the Charles's law equation.

L cm3

= 65.4Vinitial

Vinitial

cm

V = !43 r3

r !

L cm3

= 69.5Vfinal

Vfinal


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Hint 4. Convert the initial temperature to kelvins

The initial temperature of the balloon is 19.0 . What is the equivalent value on the Kelvin scale?


ANSWER:

Substitute this value for in the appropriate gas law equation.

Hint 5. Calculate the final temperature in kelvins

Calculate the outside temperature in kelvins.



The pressure and the amount of air inside the balloon remain the same. Therefore this is aCharles's law problem. We can set up the following equation and solve it for :

ANSWER:

Now you can convert this value to degrees Celsius.

ANSWER:

Since, at a constant pressure, the volume of an ideal gas is directly proportional to its temperature, theplot of volume versus temperature is a straight line. When temperature is plotted on the Celsius scale,the straight line can be extrapolated to the point where the volume is zero and the temperature is 273

. Because matter cannot have a negative volume, 273 must be the lowest possibletemperature, absolute zero.

C$

= 292Tinitial

Vfinal

Tfinal

( = (VT

)initial

VT

)final

= 310Tfinal

outside temperature = 36.9

%C$ % C$


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Part C

A cylinder with a movable piston contains 2.00 of helium, , at room temperature. More helium wasadded to the cylinder and the volume was adjusted so that the gas pressure remained the same. How manygrams of helium were added to the cylinder if the volume was changed from 2.00 to 2.70 ? (Thetemperature was held constant.)



The pressure and temperature are held constant, so this is an Avogadro's law problem. We can setup the following equation and solve it for :

Start by converting grams to moles and then solving this equation for . The number of moles

added is the difference between the final and initial molar amounts.

Hint 2. Calculate the initial number of moles

How many moles are in 2.00 of helium, ?


Hint 1. Find the molar mass of helium

What is the molar mass of ?


ANSWER:

ANSWER:

Hint 3. Calculate the final number of moles

A 2.00- cylinder contained 0.500 of helium at a certain pressure. After more helium was addedto the cylinder, the volume was changed to 2.70 to keep the pressure the same. Calculate the finalnumber of moles of the gas.


g He

L L

nfinal

( = (Vn )

initial

Vn )

finalnfinal

g He

He

molar mass of = 4.00He

= 0.500ninitial

L molL


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The pressure and temperature are held constant, so this is an Avogadro's law problem. Wecan set up the following equation and solve it for :

ANSWER:

Now that you know the initial and final numbers of moles, you can calculate the difference andconvert it to grams.

ANSWER:

According to Avogadro's law, the volume of an ideal gas is directly proportional to its molar amount. Putanother way, the law also says that equal volumes of different gases at the same temperature andpressure contain the same molar amounts. At 0 and 1 (standard conditions), 1 of anygas occupies a volume of 22.4 (standard molar volume).

Chapter 10 Question 3 - Short AnswerDescription: (a) How many molecules are there in 4.00 L of oxygen gas at 500. degree(s) C and 50.0 torr?

Part A

How many molecules are there in 4.00 of oxygen gas at 500. and 50.0 ?

ANSWER:

nfinal

( = (Vn )

initial

Vn )

final

= = 0.675nfinal

mass of helium added = = 0.700

C$ atm molL

L $ C torr


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Chapter 10 Question 23 - BimodalDescription: (a) A 0.133 mol sample of gas in a 525 mL container has a pressure of 312 torr. Thetemperature of the gas is __________°C.

Part A

A 0.133 mol sample of gas in a 525 mL container has a pressure of 312 torr. The temperature of the gas is__________°C.

ANSWER:

Chapter 10 Question 15 - AlgorithmicDescription: (a) A sample of gas (1.3 mol) occupies __________ L at 25°C and strings_1 atm.

Part A

A sample of gas (1.3 mol) occupies __________ L at 25°C and 3.0 atm.

ANSWER:

Chapter 10 Question 26 - Multiple ChoiceDescription: (a) Sodium bicarbonate is reacted with concentrated hydrochloric acid at 25.0 °C and 1.50atm. The reaction of 7.75 kg of bicarbonate with excess hydrochloric acid under these conditions willproduce __________ L of CO2.

-253

203

22.4

-20.3

20.3

.032

.78

14

.079

10.


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Part A

Sodium bicarbonate is reacted with concentrated hydrochloric acid at 25.0 °C and 1.50 atm. The reaction of7.75 kg of bicarbonate with excess hydrochloric acid under these conditions will produce __________ L ofCO2.

ANSWER:

Chapter 10 Question 20 - Multiple ChoiceDescription: (a) The molar volume of a gas at STP is __________ L.

Part A

The molar volume of a gas at STP is __________ L.

ANSWER:

Chapter 10 Question 21 - Multiple ChoiceDescription: (a) How many moles of gas are there in a 45.0 L container at 25.0 °C and 500.0 mm Hg?

Part A

How many moles of gas are there in a 45.0 L container at 25.0 °C and 500.0 mm Hg?

1.50 x 103

1.82 x 103

2.85 x 104

1.82 x 104

8.70 x 102

62.36

14.7

22.4

1.00

0.08206


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ANSWER:

Chapter 10 Question 22 - AlgorithmicDescription: (a) Calcium hydride ((CaH)_2) reacts with water to form hydrogen gas: (CaH)_2(s) + (2H)_2 O(l) rightarrow (Ca(OH))_2 (aq) + (2H)_2 (g) How many grams of (CaH)_2 are needed to generate strings_6L of H_2 gas at a pressure of strings_7 atm and...

Part A

Calcium hydride ( ) reacts with water to form hydrogen gas:

How many grams of are needed to generate 45.0 L of gas at a pressure of 0.811 atm and atemperature of 32 °C?

ANSWER:

Chapter 10 Question 28 - BimodalDescription: (a) The molecular weight of a gas is __________ g/mol if 6.7 g of the gas occupies 6.3 L atSTP.

Part A

The molecular weight of a gas is __________ g/mol if 6.7 g of the gas occupies 6.3 L at STP.

6.11

18.4

207

0.630

1.21

CaH2

(s) + O(l)# (aq) + (g)CaH2 2H2 Ca(OH)2 2H2

CaH2 H2

30.7

61.4

43.4

123

0.729


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ANSWER:

Chapter 10 Question 26 - BimodalDescription: (a) The density of N2O at 1.53 atm and 45.2 °C is __________ g/L.

Part A

The density of N2O at 1.53 atm and 45.2 °C is __________ g/L.

ANSWER:

Chapter 10 Question 60 - BimodalDescription: (a) CO (5.00 g) and CO2 (5.00 g) were placed in a 750.0 mL container at 50.0 °C. The partialpressure of CO in the container was __________ atm.

Part A

CO (5.00 g) and CO2 (5.00 g) were placed in a 750.0 mL container at 50.0 °C. The partial pressure of CO inthe container was __________ atm.

ANSWER:

27

3.0 ! 102

1.8 ! 10-2

24

3.6 x 103

2.58

9.99

1.76

0.388

18.2


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Chapter 10 Question 48 - BimodalDescription: (a) A sample of He gas (3.0 L) at 5.6 atm and 25 °C was combined with 4.5 L of Ne gas at 3.6atm and 25 °C at constant temperature in a 9.0 L flask. The total pressure in the flask was __________ atm.Assume the initial pressure in the flask was...

Part A

A sample of He gas (3.0 L) at 5.6 atm and 25 °C was combined with 4.5 L of Ne gas at 3.6 atm and 25 °C atconstant temperature in a 9.0 L flask. The total pressure in the flask was __________ atm. Assume theinitial pressure in the flask was 0.00 atm and the temperature upon mixing was 25 °C.

ANSWER:

Problem 10.72Description: A mixture of gases contains m_1 of N_2, m_2 of H_2, and m_3 of (NH)_3. The total pressureof the mixture is P. (a) What is the partial pressure of N_2? (b) What is the partial pressure of H_2? (c) Whatis the partial pressure of (NH)_3?

A mixture of gases contains 10.35 of , 1.84 of , and 7.95 of . The total pressure of the mixture is1.75 .

Part A

What is the partial pressure of ?

ANSWER:

6.29

4.02

0.292

10.3

1.60

24

2.6

9.2

1.0

3.7

g N2 g H2 g NH3atm

N2


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Part B


ANSWER:

Part C


ANSWER:

= = 0.370 PN2 atm

H2

= = 0.913 PH2 atm

NH3

= = 0.467 PNH3 atm


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My Courses Chemistry: The Central Science, 12e Brown/LeMay ...€¦ · Signed in as Daniel Semenick , Instructor Help Sign Out Chapter 10 Quiz Due: 9:58pm on Thursday, October 30,