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44 Cards in this Set
- Front
- Back
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What three different physical forms can matter exist in?
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Gas, liquid, and solid
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How do the atoms or molecules in a gaseous sample move relative to each other?
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They move rapidly and are far apart from each other
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What type of intermolecular forces exist between gas particles?
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Only weak ones exist
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What does this result in?
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It results in the ability to expand to fill any volume and to take on the shape of a container
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How compressible are gases?
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They are easily but not infinitely compressible
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What is the state of a gaseous sample defined by?
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Pressure, Volume, Temperature, and number of moles
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What is the conversion from atmospheres to torr?
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1 atm = 760 mm Hg = 760 torr
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What are standard temperature and pressure?
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The conditions of 273.15K (0C) and 1 atm
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What does an ideal gas represent?
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A hypothetical gas whose molecules have no intermolecular forces and occupy no volume
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When do gases actually deviate from this idealized behavior?
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They deviate at low pressures and high temperatures
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What is Boyle’s Law?
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It says that for a given gaseous sample held at constant temperature, the volume of a gas is inversely proportional to its pressure
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What is this equation?
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P1V1 = P2V2 or PV = k
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What is Charles’ Law?
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It states that at constant pressure, the volume of a gas is directly proportional to its absolute temperature
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What is absolute temperature expressed by?
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It can be calculated from Tk = Tc + 273.15
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What is the equation for Charles’ Law?
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V1/T1 = V2/T2 or V/T = k
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What is Avogadro’s Principle?
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It states that for all gases at a constant temperature and pressure, the volume of the gas will be directly proportional to the number of moles of gas present
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What is the equation for this?
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n1/V1 = n2/V2 or n/V = k
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What is the ideal gas law?
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It shows the relationship between pressure, volume, temperature, and number of moles
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What is the equation?
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PV = nRT
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What is density?
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It is defined as the mass per unit volume of a substance, and for gases, is usually expressed in units of g/L
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What is the equation for density?
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d = m/V
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What is the volume of a mole of gas at STP?
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It is 22.4L
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What are deviations due to pressure?
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At moderately high pressure (a few hundred atmospheres) a gas’ volume is less than would be predicted by the ideal gas law, due to intermolecular attraction
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What happens at extremely high pressures?
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The size of the particles becomes relatively large compared to the distance between them, and this causes the gas to take up a larger volume than would be predicted by the ideal gas law
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What are deviations due to temperature?
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As the temperature of a gas is reduced toward its condensation point (which is the same as its boiling point), intermolecular attraction causes the gas to have a smaller volume than would be predicted by the ideal gas law
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What does this mean?
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The closer the temperature of a gas is to its boiling point, the less ideal is its behavior
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What is the pressure exerted by each individual gas called?
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It is called the partial pressure of that gas
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What does Dalton’s Law of Partial Pressures state?
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It says that the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual components
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What is the equation?
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Pt = Pa + Pb + Pc + …
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How can the partial pressure of a gas be derived?
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It is related to its mole fraction
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What is the equation?
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Pa = PtXa
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What are the assumptions of the kinetic molecular theory?
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It says that gases are made up of particles whose volumes are negligible compared to the container volume. Gas atoms or molecules exhibit no intermolecular attractions or repulsions. Gas particles are in continuous, random motion, undergoing collisions with other particles and the container walls. Collisions between any two gas particles are elastic, meaning that there is no overall gain or loss of energy. The average kinetic energy of gas particles is proportional to the absolute temperature of the gas, and is the same for all gases at a given temperature
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What is the average kinetic energy of a gas particle?
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It is proportional to the absolute temperature of the gas
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What is the equation?
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KE = _ mv2 = 3/2kT
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What does this equation infer?
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The speed of a gas molecule is related to its absolute temperature
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How are the speeds of gases defined?
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They are defined in terms of their average molecular speed
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When does diffusion occur?
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It occurs when gas molecules diffuse through a mixture
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What does diffusion account for?
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It accounts for the fact that an open bottle of perfume can quickly be smelled across a room
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What does the kinetic molecular theory of gases predict concerning the speed of heavier gases compared to lighter gasses?
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Heavier gas molecules diffuse more slowly than lighter ones because of their differing average speeds
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What are the rates at which two gases diffuse related by?
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The rate that two gases diffuse are inversely proportional to the square root f their molar masses
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What is the equation?
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r1/r2 = (MM2)/(MM1)1/2
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What is effusion?
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It is the flow of gas particles under pressure form one compartment to another through a small opening
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What are the rates of effusion proportional to?
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They are proportional to the average speeds
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What is the equation for this?
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r1/r2 = (MM2)/(MM1)1/2
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