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Daily Science pg. 92

Daily Science pg. 92. Reactions that require energy are called what? Which phase changes release energy? What is the triple point of a substance? What are 3 units of pressure for a gas?. Gas Laws. Pg. 95 foldable. Variable of gases. Number of gas particles present Temperature Pressure

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Daily Science pg. 92

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  1. Daily Science pg. 92 • Reactions that require energy are called what? • Which phase changes release energy? • What is the triple point of a substance? • What are 3 units of pressure for a gas?

  2. Gas Laws Pg. 95 foldable

  3. Variable of gases • Number of gas particles present • Temperature • Pressure • Volume • Be sure to watch units!

  4. Boyle’s Law • Definition- the volume of a gas held at a constant temperature varies INVERSLY with pressure • Decrease in volume represents an increase in pressure • Formula- P1V1=P2V2 • Example: The volume of a gas at 99 kPa is 300.00 mL. If the pressure is increased to 188 kPa, what will be the new volume?

  5. Charles’s Law • Definition- the volume of a gas is DIRECTLY proportional to its Kelvin temperature at constant pressure. • Volume goes increases, temperature increases • Formula- V1/T1 =V2/T2 or V1T2 =V2T1 • Converting from Celsius to Kelvin- C +273 • Example- A gas at 89 oC occupies a volume of .67 L. At what Celsius temperature will the volume increase to 1.12 L?

  6. Gay-Lussac’s Law • Definition- the pressure of a gas is DIRECTLY proportional with temperature if volume is held constant. • Formula- P1/T1 =P2/T2 or P1T2 = P2T1 • Example: A gas in a sealed container has a pressure of 125 kPa at a temperature of 30.0 oC. If the pressure in the container is increased to 201 kPa, what is the new temperature?

  7. Combined gas law • Definition- states the relationship of temp, press, and vol, for a fixed amount of gas. All variables have the same relationship as in other gas laws. • Formula- P1V1/T1 = P2V2/T2 • Example: A helium filled balloon at sea level has a volume of 2.1 L at 0.998 atm and 36 oC. If it is released and rises to an elevation at which the pressure is 0.900 atm and the temperature is 28 oC, what will be the new volume?

  8. Ideal Gas Law • Definition- describes the physical behavior of an ideal gas in terms of pressure, temperature, volume, and number of moles present. • Ideal- assumes have no intermolecular attraction • Formula – PV=nRT • R is the ideal gas constant = 0.0821 (if P is in atm)= 8.314 (if P is in kPa) • n= the number of moles • Example- If the pressure exerted by a gas at 25 oC in a volume of 0.044 L is 3.81 atm, how many moles of gas are present?

  9. Variations of the Ideal gas law • Can find molar mass • n= given mass/mm • Formula • PV=mRT/mm • Can find density • d=m/v • Formula • P(mm)/RT=m/v Example: How many grams are present in a sample that has a molar mass of 70 g/mol and occupies a 2.00 L container at 117 kPa and 35.1 oC. Example: What is the density of a gas at 1.0 atm at 22 oC that has a molar mass of 44 g/mol?

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