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Torricelli’s Barometer

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A simple manometer for measuring gas pressure in a container

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Robert Boyle

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A J-tube similar to the one used by Boyle

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Increased pressure leads to decreased volume

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Table 5.1 Actual Data from Boyle's Experiment

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Plotting Boyle's Data

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As pressure increases, the volume of SO2 decreases

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As pressure increases, the volume decreases

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Antoine and Marie Lavoisier(Painting by Jacques-Louis David)

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Empress Eugenie of France(Painting by Franz Winterhalter)

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Prof. Jacques Charles

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Increasing the temperature of a gas (at constant pressure) increases its volume.

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Plots of V versus T(Celsius) for several gases

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Plots of V versus T using the Kelvin scale for temperature

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At constant volume, pressure increases in proportion to Kelvin temperature.

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Boyle’s law: PV = k (for constant T)Charles’s law: V = kT (for constant P)Gay-Lussac’s law: P = kT (for constant V)

COMBINE ALL THREE:

PV = k T or

PV/T = k for any sample

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PV = PVT T

(for any sample of gas under two sets of conditions)

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One mole of any gas at S.T.P. (273 K, 1.0 atm.) occupies 22.4 L and just fits into this box

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At a given temperature and pressure, each of these balloons holds the same number of moles.

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The partial pressure of each gas in a mixture depends on the number of moles of that gas.

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PV = n RT

R = 0.0821 L atm / mol K

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Kinetic molecular theory models gases as large numbers of randomly moving particles of negligible volume that interact with other particles (and container walls) only by collision.

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The End

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The production of oxygen by thermal decomposition of KClO3

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Reaction of zinc with HCl

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Effusion of a gas into an evacuated chamber

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Relative molecular speed distribution of H2 and UF6

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NH3 gas and HCl gas diffuse toward each other and react to form solid NH4Cl

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Velocity distribution of N2 molecules at 3 different temperatures

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Slower Molecules Produce a Lower Pressure

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Gas at low concentration has relatively fewer interactions between particles

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Pairwise interactions among gas particles

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Velocity distribution of O2 Molecules at STP

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The volume taken up by the gas particles themselves is less important (a) at low pressure than (b) at high pressure.

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Molecular Sieve Model

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Inflated Air Bags

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The pressure exerted by the atomsphere can be demonstrated by boiling water in a large metal can

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Acid Rain: Statue in 1990

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Schematic diagram of the process for “scrubbing” sulfur dioxide emissions from

stack gases in power plants

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An environmental officer testing the pH of water.

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Atmospheric composition of dry air near sea level

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Variation of temperature (blue) and pressure (dashed lines) with altitude

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Molar volumes for various gases at 0°C and 1 atm

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Plot of PV versus P for several non-ideal gases at low pressure

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Plot of PV/nRT versus P for Nitrogen gas at 3 temperatures

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Plot of PV versus P for 1 mol of ammonia.

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Plots of PV/nRT versus P for Several Gases (at 200K)

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Values of the van der Waals constants for selectedgases

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Increased volume due to increased moles of gas at constant temperature and pressure

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The ratio of the volumes of gaseous N2 and liquid N2 is 22.4/0.035=640 and the spacing of the molecules is

9 times farther apart in N2(g).

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