# Gas Laws Continued. Atmospheric Pressure Let’s calculate the amount of atmospheric pressure pressing on our bodies! Step 1: Calculate body surface area.

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Gas Laws Continued

Atmospheric Pressure Let’s calculate the amount of atmospheric pressure pressing on our bodies! Step 1: Calculate body surface area. Use this equation: M 2 = (Ht in Cm) 0.3964 x (Wt in Kg) 0.5378 x 0.024265

Atmospheric Pressure Conversions: 1in = 2.54 cm 1lb =.45 Kg Step 2: Next convert Meters 2 into Inches 2. –One Meter = 39.36 Inches. –1M 2 = 1550 In 2. Step 3: Multiply your answer from step one with step two. Step 4: Multiply your answer from step 4 by 13.0 psi (PSI in Fort Collins)

Example Height = 69 in –175.26 cm Weight = 130 lbs – 59 Kg (175.2cm) 0.3964 x (59Kg) 0.5378 x0.024265= 1.676 M 2 1.676M 2 x 1550 in 2 = 2597.8 in 2 2597.8in 2 x 12.5psi = 32,472.5 lbs 32,500.00 Lbs

Put it into Perspective This is the same as three full grown elephants. This is the same as 12 Honda Civics. This is the same as one semi-truck.

Ideal Gas Law The Ideal Gas Law allows us to account for the number of moles of gas in a system. The Ideal Gas Law automatically adjusts to standard temperature and pressure using the Ideal Gas Constant (R).

Ideal Gas Law PV=nRT Pressure is proportional to temperature. (T) Pressure is proportional to number of moles. (n) Pressure is inversely proportional to volume. (V)

The Universal Gas Constant R is the universal gas constant that corrects for systems not at STP. The value of R varies depending on which units of pressure are being used. R = 0.0821 L  atm/mol  K R = 62.4 L  mmHg/mol  K R = 8.31 L  kPa/mol  K

Dalton’s Law John Dalton (1766-1844) At a constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of those gases.

Dalton’s Law Each gas exerts its own pressure as if the other gases were not there. You can add the individual pressures of each gas to obtain the total pressure of a gas mixture. Mathematical Expression –P total =P 1 +P 2 +P 3 +P 4 …………

The “Litter Box” Equation  = dRT/P A useful version of the Ideal Gas Law involved molar mass and gas density. If gas density (d in g/L) is known, molar mass (  in g/mol) can easily be calculated. We call it the “litter box” equation because a kitty says “mu”, takes a “P”, and kicks “dRT” over it.

Review Which line on the graph at the left best illustrates Boyle’s Law of pressure and volume? If you said “D”, you are correct! Pressure VolumeVolume A B C D

Review Which line on the graph shows Charles’ Law, the relationship between temperature and volume? If you said “A” you are correct. Temperature VolumeVolume A B C D

Review Which line best illustrates Gay- Lussac’s law of pressure vs. temperature? If you said “A” again, you are correct. Temperature PressurePressure A B C D

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