Gases Flashcards

1
Q

Kinetic molecular theory

A
  • collection of particles are in constant motion
  • no attraction or repulsions between molecules; they collide like billiard balls
  • large amount of space between particles relative to the size of the particles themselves
  • Particles move with increased speed when temp. is increased.
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2
Q

Gas molecules are in ____________.

A

constant motion

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3
Q

What happens when gas molecules move and strike a surface?

A

they push or exert force on a surface.

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4
Q

Define pressure

A

the total amt. of force exerted by gas molecules hitting the entire surface at any one instant

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5
Q

How is pressure found?

A

P=F/A
P= pressure
F= force
A= area

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6
Q

How is pressure created with a gas?

A

it is the result of the constant movement of gas molecules and collisions with the surfaces around them.

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7
Q

What are the factors that the pressure of a gas depends on?

A

1) the number of gas particles in a given volume
2) volume of the container
3) average speed of the gas particles

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8
Q

How is air pressure measured?

A

with a barometer

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9
Q

How does a barometer work?

A

A column of mercury is supported by air pressure. The force of the air on the surface of the mercury balanced by the pull of gravity on the column of mercury.

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10
Q

An increase in particle in a volume of space will increase what?

A

pressure

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11
Q

atm

A

atmosphere

1 atm (exactly) = 760 (exactly) mmHG = 760 torr (exactly) = 14.7 psi, lbs/in squared

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12
Q

What are the common units of pressure?

A
Pascals (Pa)
Kilopascals (kPa)
Atmosphere (atm)
Millimeters of mercury (mmHg)
Inches of Mercury (inHg)
Torr (torr)
Pounds per square inch (psi, lbs./in squared)
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13
Q

mmHg

A

Millimeters of mercury

1 atm (exactly) = 760 (exactly) mmHG = 760 torr (exactly) = 14.7 psi, lbs/in squared

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14
Q

torr

A

Torr (unit of pressure)

1 atm (exactly) = 760 (exactly) mmHG = 760 torr (exactly) = 14.7 psi, lbs/in squared

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15
Q

psi

A

Pounds per square inch

1 atm (exactly) = 760 (exactly) mmHG = 760 torr (exactly) = 14.7 psi, lbs/in squared

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16
Q

Boyle’s Law

A
  • Pressure of a gas is inversely proportional to its volume.
  • temp is constant
  • amt. of gas is constant
  • as P increases V decreases by same factor
  • PxV= constant
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17
Q

What is the formula for Boyle’s law?

A

P1xV1=P2xV2

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18
Q

According to Boyle’s law what happens when the volume a gas occupies is cut in half?

A

the pressure of the gas is doubled (as long a temperature and amt. of gas stays the same.)

19
Q

Charles’ law

A
  • Volume is directly proportional to temperature
  • Pressure is constant
  • amt. of gas is constant
  • as T increases, V increases
  • V= constant x T
  • TEMP IS ALWAYS MESURED IN KELVINS
20
Q

According to Charles’ law what happens to a gas when it is heated, when it is chilled?

A

When heated the gas expands and density decreases, when chilled the gas condenses and density increases.

21
Q

What is the Formula for Charles’ law?

A

V1/T1 = V2/T2

22
Q

According to Charles’ law density decreases when a gas is heated, why?

A

because the molecules have a higher kinetic energy and they have more energy to push out.

23
Q

What is the combined gas law?

A

Boyle’s law and Charles’ law put together; this law predicts what will happen to the volume of a gas when temp. and pressure changes.

24
Q

What is the formula for the combined gas law?

A

(P1)(V1)/(T1) = (P2)(V2)/(T2)

25
Q

All gas laws are only valid with __________.

A

Kelvins

26
Q

Avogadro’s law

A

Volume is directly proportional to the number of gas molecules.

  • V= constant x n
  • P and T are constant
  • more gas molecules larger volume
  • number of gas molecules is counted in moles.
27
Q

What is the formula for Avogadro’s law?

A

V1/n1 = V2/n2

28
Q

Ideal Gas law

A
  • all the gas laws combined
  • R is gas constant
  • R depends on P and V but 0.0821 atmxL/molxK will be used
  • because of this P needs to be in atm and V needs to be in liters
29
Q

When is the ideal gas law used and when is the combined gas law used?

A

the ideal gas law is used when a gas is at one condition, the combined gas law is used when a gases’ condition is changing.

30
Q

What is the formula for the Ideal gas law?

A

PV = nRT

31
Q

What are ideal gas conditions?

A
  • high temperature
  • low pressure
  • particle size is small compared to space between particles
  • interactions between particles are insignificant
32
Q

What are Real (non-ideal) gas conditions?

A
  • low temp
  • high pressure
  • particle size is signif. compared to space btwn. particles
  • interactions btwn. particles are signif.
33
Q

What is partial pressure?

A

Each gas in a mixture exerts a pressure independent of the other gases in a mixture. The pressure of a component gas in a mixture is called a partial pressure. The sum of all the partial pressures is equal to the total pressure.

34
Q

Dalton’s Law of partial pressure

A

P total = P gas A + P gas B + P gas C + ….

35
Q

How do you find a partial pressure?

A

multiply the total pressure of a gas mixture by the percent turned into a decimal of the fractional component of the mixture.

P He = (0.800)(1.0 atm) = 0.80 atm

(The component gas = percent divided by 100) to get decimal

36
Q

What partial pressure of O2 are our bodies adapted to breath?

A

0.21 atm

37
Q

hypoxia

A

low oxygen levels in blood; partial pressures of O2 less than 0.1 will lead to hypoxia, unconsciousness or death

38
Q

When climbers are climbing mt. Everest they need O2 cylinders to prevent what?

A

hypoxia

39
Q

When you feel the pressure of air what is felt?

A

one pressure; not individual pressures

40
Q

The higher the percentage of a gas in a mixture the more it ______ to total pressure of the mixture.

A

contributes

41
Q

Standard conditions

A
  • keeping conditions the same

- STP

42
Q

STP

A

Standard temp. and pressure.

-standard pressure 1.00 atm
-standard temp. 273 K
0 degrees C

43
Q

How much volume will one mole of any gas at STP occupy?

A

22.4 L (THIS IS CALLED MOLAR VOLUME) and can be used as a conversion factor. As long as work is done at STP

1 mol = 22.4 L

44
Q

Molar volume

A

There is so much room between molecules in the gaseous state that volume is not effected by the size of molecules (under ideal conditions).