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In the text, it was shown that N / V = 2 . 68 × 10 25 m 3 size 12{N/V=2 "." "68" times "10" rSup { size 8{"25"} } `m rSup { size 8{ - 3} } } {} for gas at STP. (a) Show that this quantity is equivalent to N / V = 2 . 68 × 10 19 cm 3 , size 12{N/V=2 "." "68" times "10" rSup { size 8{"19"} } `"cm" rSup { size 8{ - 3} } ,} {} as stated. (b) About how many atoms are there in one μm 3 size 12{"μm" rSup { size 8{3} } } {} (a cubic micrometer) at STP? (c) What does your answer to part (b) imply about the separation of atoms and molecules?

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Calculate the number of moles in the 2.00-L volume of air in the lungs of the average person. Note that the air is at 37 . 0 º C size 12{"37" "." 0°C} {} (body temperature).

7 . 86 × 10 2 mol size 12{7 "." "86" times "10" rSup { size 8{ - 2} } `"mol"} {}

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An airplane passenger has 100 cm 3 size 12{"100"" cm" rSup { size 8{3} } } {} of air in his stomach just before the plane takes off from a sea-level airport. What volume will the air have at cruising altitude if cabin pressure drops to 7 . 50 × 10 4 N/m 2 ? size 12{7 "." "50"´"10" rSup { size 8{4} } " N/m" rSup { size 8{2} } } {}

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(a) What is the volume (in km 3 size 12{"km" rSup { size 8{3} } } {} ) of Avogadro’s number of sand grains if each grain is a cube and has sides that are 1.0 mm long? (b) How many kilometers of beaches in length would this cover if the beach averages 100 m in width and 10.0 m in depth? Neglect air spaces between grains.

(a) 6 . 02 × 10 5 km 3 size 12{6 "." "02" times "10" rSup { size 8{5} } `"km" rSup { size 8{3} } } {}

(b) 6 . 02 × 10 8 km size 12{6 "." "02" times "10" rSup { size 8{8} } `"km"} {}

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An expensive vacuum system can achieve a pressure as low as 1 . 00 × 10 7 N/m 2 size 12{1 "." "00"´"10" rSup { size 8{ +- 7} } " N/m" rSup { size 8{2} } } {} at 20 º C size 12{"20"°C} {} . How many atoms are there in a cubic centimeter at this pressure and temperature?

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The number density of gas atoms at a certain location in the space above our planet is about 1 . 00 × 10 11 m 3 , size 12{1 "." "00" times "10" rSup { size 8{"11"} } `m rSup { size 8{ - 3} } ,} {} and the pressure is 2 . 75 × 10 10 N/m 2 size 12{2 "." "75"´"10" rSup { size 8{ +- "10"} } " N/m" rSup { size 8{2} } } {} in this space. What is the temperature there?

73 . 9 º C size 12{ - "73" "." 9°C} {}

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A bicycle tire has a pressure of 7 . 00 × 10 5 N/m 2 size 12{7 "." "00"´"10" rSup { size 8{5} } " N/m" rSup { size 8{2} } } {} at a temperature of 18 . 0 º C size 12{"18" "." 0°C} {} and contains 2.00 L of gas. What will its pressure be if you let out an amount of air that has a volume of 100 cm 3 size 12{"100"" cm" rSup { size 8{3} } } {} at atmospheric pressure? Assume tire temperature and volume remain constant.

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A high-pressure gas cylinder contains 50.0 L of toxic gas at a pressure of 1 . 40 × 10 7 N/m 2 size 12{1 "." "40"´"10" rSup { size 8{7} } " N/m" rSup { size 8{2} } } {} and a temperature of 25 . 0 º C size 12{"25" "." 0°C} {} . Its valve leaks after the cylinder is dropped. The cylinder is cooled to dry ice temperature ( 78 . 5 º C ) size 12{ \( –"78" "." 5°C \) } {} to reduce the leak rate and pressure so that it can be safely repaired. (a) What is the final pressure in the tank, assuming a negligible amount of gas leaks while being cooled and that there is no phase change? (b) What is the final pressure if one-tenth of the gas escapes? (c) To what temperature must the tank be cooled to reduce the pressure to 1.00 atm (assuming the gas does not change phase and that there is no leakage during cooling)? (d) Does cooling the tank appear to be a practical solution?

(a) 9 . 14 × 10 6 N/m 2 size 12{9 "." "14" times "10" rSup { size 8{7} } `"N/m" rSup { size 8{2} } } {}

(b) 8 . 23 × 10 6 N/m 2 size 12{8 "." "23" times "10" rSup { size 8{7} } `"N/m" rSup { size 8{2} } } {}

(c) 2.16 K

(d) No. The final temperature needed is much too low to be easily achieved for a large object.

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Find the number of moles in 2.00 L of gas at 35 . 0 º C size 12{"35" "." 0°C} {} and under 7 . 41 × 10 7 N/m 2 size 12{7 "." "41"´"10" rSup { size 8{7} } " N/m" rSup { size 8{2} } } {} of pressure.

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Calculate the depth to which Avogadro’s number of table tennis balls would cover Earth. Each ball has a diameter of 3.75 cm. Assume the space between balls adds an extra 25.0% to their volume and assume they are not crushed by their own weight.

41 km

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(a) What is the gauge pressure in a 25 . 0 º C size 12{"25" "." 0°C} {} car tire containing 3.60 mol of gas in a 30.0 L volume? (b) What will its gauge pressure be if you add 1.00 L of gas originally at atmospheric pressure and 25 . 0 º C size 12{"25" "." 0°C} {} ? Assume the temperature returns to 25 . 0 º C size 12{"25" "." 0°C} {} and the volume remains constant.

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(a) In the deep space between galaxies, the density of atoms is as low as 10 6 atoms/m 3 , size 12{"10" rSup { size 8{6} } " atoms/m" rSup { size 8{3} } ,} {} and the temperature is a frigid 2.7 K. What is the pressure? (b) What volume (in m 3 size 12{m rSup { size 8{3} } } {} ) is occupied by 1 mol of gas? (c) If this volume is a cube, what is the length of its sides in kilometers?

(a) 3 . 7 × 10 17 Pa size 12{3 "." 7 times "10" rSup { size 8{ - "17"} } `"Pa"} {}

(b) 6 . 0 × 10 17 m 3 size 12{6 "." 0 times "10" rSup { size 8{"17"} } `m rSup { size 8{3} } } {}

(c) 8 . 4 × 10 2 km size 12{8 "." 4 times "10" rSup { size 8{2} } `"km"} {}

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Questions & Answers

what there factors affect the surface tension of a liquid
Promise Reply
formula for impedance
muyiwa Reply
ehat is central forces
Nita Reply
what is distance?
Jonathan Reply
What does mean ohms law imply
Victoria Reply
ohms law state that the electricity passing through a metallic conductor is directly proportional to the potential difference across its end
muyiwa
what is matter
folajin Reply
Anything that occupies space
Kevin
Any thing that has weight and occupies space
Victoria
Anything which we can feel by any of our 5 sense organs
Suraj
Right
Roben
thanks
Suraj
what is a sulphate
Alo
any answers
Alo
the time rate of increase in velocity is called
Blessing Reply
acceleration
Emma
What is uniform velocity
Victoria
Greetings,users of that wonderful app.
Frank Reply
how to solve pressure?
Cruz Reply
how do we calculate weight and eara eg an elefant that weight 2000kg has four fits or legs search of surface eara is 0.1m2(1metre square) incontact with the ground=10m2(g =10m2)
Cruz
P=F/A
Mira
can someone derive the formula a little bit deeper?
Bern
what is coplanar force?
OLADITI Reply
forces acting and lying on d same plane
Promise
what is accuracy and precision
Peace Reply
How does a current follow?
Vineeta Reply
follow?
akif
which one dc or ac current.
akif
how does a current following?
Vineeta
?
akif
AC current
Vineeta
AC current follows due to changing electric field and magnetic field.
akif
you guys are just saying follow is flow not follow please
Abubakar
ok bro thanks
akif
flows
Abubakar
but i wanted to understand him/her in his own language
akif
but I think the statement is written in English not any other language
Abubakar
my mean that in which form he/she written this,will understand better in this form, i write.
akif
ok
Abubakar
ok thanks bro. my mistake
Vineeta
u are welcome
Abubakar
what is a semiconductor
Vineeta Reply
substances having lower forbidden gap between valence band and conduction band
akif
what is a conductor?
Vineeta
replace lower by higher only
akif
convert 56°c to kelvin
Abubakar
How does a current follow?
Vineeta
A semiconductor is any material whose conduction lies between that of a conductor and an insulator.
AKOWUAH
what is Atom? what is molecules? what is ions?
Abubakar Reply
atoms are the smallest unit of an element which is capable of behaving as a single unit
Promise
a molecule is d smallest unit of a substances capable of independent existence and can also retain the chemical proper ties of that substance
Promise
an ion is referred to as freely moving charged particles
Promise
What is a molecule
Samuel Reply
Is a unit of a compound that has two or more atoms either of the same or different atoms
Justice
A molecule is the smallest indivisible unit of a compound, Just like the atom is the smallest indivisible unit of an element.
Rachel
what is a molecule?
Vineeta
Practice Key Terms 4

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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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