Gases Lecture 1 PDF

Delta University for Science and Technology Faculty of Applied Health Gases Presented by Ass. Prof. Nesma Mamdouh Bayoumy Fall 2024 States of matter There are four states of Matter Ø Solid Ø Liquid Ø Gas Ø Plasma Based on: ØParticle arra...

Delta University for Science and Technology Faculty of Applied Health Gases Presented by Ass. Prof. Nesma Mamdouh Bayoumy Fall 2024 States of matter There are four states of Matter Ø Solid Ø Liquid Ø Gas Ø Plasma Based on: ØParticle arrangement ØEnergy of particles ØDistance between particles  Kinetic Theory of Matter Matter is made up of particles which are in continual random motion.  STATES OF MATTER SOLIDS Particles of solids are tightly packed, vibrating about a fixed position. Solids have a definite shape and a definite volume. Heat  STATES OF MATTER LIQUID § Particles of liquids are tightly packed, but are far enough apart to slide over one another. § Liquids have an indefinite shape and a definite volume. Heat  STATES OF MATTER GAS § Particles of gases are very far apart and move freely. § Gases have an indefinite shape and an indefinite volume. Heat  STATES OF MATTER PLASMA § A plasma is an ionized gas. § A plasma is an excellent conductor of electricity and is affected by magnetic fields. § Plasmas, like gases have an indefinite shape and an indefinite volume. Plasma is the common state of matter Conclusion STATES OF MATTER SOLID LIQUID GAS PLASMA Tightly packed, in a Close together with no Well separated with no Has no definite volume regular pattern regular arrangement. regular arrangement. or shape and is Vibrate, but do not Vibrate, move about, Vibrate and move composed of electrical move from place to and slide past each freely at high speeds charged particles place other  STATES OF MATTER SOLIDS Particles of solids are tightly packed, vibrating about a fixed position. Solids have a definite shape and a definite volume. Heat Characteristics of Gases Gases assume the volume and shape of their containers. 01 Gases will completely mix when confined to the same 02 container. 03 Gases have much lower densities than liquids and solids. 04 Gases are the most compressible state of matter. 05 When pressure is applied to a gas : Its volume decreases. Ø Temperature Always use absolute temperature (Kelvin) when working with gases. ºF -459 32 212 ºC -273 0 100 K 0 273 373 °C = (°F - 32) 5 9 K = ºC + 273 PRESSURE: There are many techniques for measuring pressure: Ø Barometer measures atmospheric pressure. Ø Manometer measures contained gas pressure. KEY UNITS AT SEA LEVEL 101.325 kPa (kilopascal) 1 atm force N pressure = kPa = 2 760 mm Hg area m 760 torr 14.7 psi  Pressure Conversions A. What is 475 mm Hg expressed in atm? (0.625 atm) B. The pressure of a tire is measured as 29.4 psi. What is this pressure in mm Hg? (1.52 x 103 mm Hg) C. What is 2 atm expressed in torr? (1520 Torr) D. The pressure of a tire is measured as 32.0 psi. What is this pressure in kPa? (22.15 KPa) STP (Standard Temperature and Pressure) Standard Temperature & Pressure 0°C 273 K 1 atm 101.325 kPa Gas Laws  Boyle’s Law vDetermined the relation between V & P. v Pressure and volume are inversely related at constant temperature. vPV = K For two different gases Robert Boyle Chemist & Natural vBoyle’s Law: P1V1 = P2V2 Philosopher  Boyle’s Law Volume Pressure P·V (mL) (torr) (mL·torr) 3 10.0 760.0 7.60 x 10 3 20.0 379.6 7.59 x 10 3 30.0 253.2 7.60 x 10 3 40.0 191.0 7.64 x 10 P PV = k V Charles’ Law: v Determined the relation between V & T. vVolume of a gas varies directly with the absolute temperature at constant pressure. v V = KT For two different gases Jacques- Charles’ Law: V1/T1 = V2/T2 Alexandre Charles Mathematician, Physicist, Inventor Charles’ Law: Volume Temperature V/T (mL) (K) (mL/K) 40.0 273.2 0.146 44.0 298.2 0.148 47.7 323.2 0.148 51.3 348.2 0.147 V V =k T T  Avogadro’s Law vDetermined the relation between V & n. vAt constant temperature and pressure, the volume of a gas is directly related to the number of moles. vV = K n For two different gases: Avogadro’s Law: V1/n1=V2/n2 Amedeo Avogadro Physicist  Gay-Lussac’s Law Temperature Pressure P/T (K) (torr) (torr/K) 248 691.6 2.79 273 760.0 2.78 298 828.4 2.78 373 1,041.2 2.79 P P =k T T  Gay-Lussac Law vDetermined the relation between P& T. vpressure is directly proportional to temperature at constant volume and no. of moles. Joseph-Louis Gay-Lussac vP = k T Experimentalist For two different gases: v P1 / T1 = P2 / T2  Combined Gas Law The combined gas law describes the relationship between pressure, volume, temperature and number of moles. Boyle’s law: V a P (at constant n and T) Charles’ law: V a T (at constant n and P) Avogadro’s law: V a n (at constant P and T) PV = nRT R is the gas constant For two different gases: P1V1 P2V2 T1 T2 Gas Law Problems A gas occupies 100. mL at 150. kPa. Find its volume at 200. kPa. BOYLE’S LAW GIVEN: P­ V¯ WORK: V1 = 100. mL P1V1T2 = P2V2T1 P1 = 150. kPa (150.kPa)(100.mL)=(200.kPa)V2 V2 = ? V2 = 75.0 mL P2 = 200. kPa  Gas Law Problems A gas occupies 473 cm 3 at 36°C. Find its volume at 94°C. CHARLES’ LAW GIVEN: T­ V­ WORK: V1 = 473 cm 3 P1V1T2 = P2V2T1 T1 = 36°C = 309K (473 cm )(367 3 K)=V2(309 K) V2 = ? T2 = 94°C = 367K V2 = 562 cm3 Gas Law Problems A gas occupies 7.84 cm3 at 71.8 kPa & 25°C. Find its volume at STP. COMBINED GAS LAW GIVEN: P­ T¯ V¯ WORK: V1 = 7.84cm3 P1V1T2 = P2V2T1 P1 = 71.8 kPa (71.8 kPa)(7.84 cm )(273 K) 3 T1 = 25°C = 298 K =(101.325 kPa) V2 (298 K) V2 = ? P2 = 101.325 kPa V2 = 5.09 cm 3 T2 = 273 K  Methane is compressed in a closed 15.8 dm³ container at 101.3 KPa. If the volume drops to 8.7 dm³ and the temperature begins at 25°C and then drops to18°C, calculate the pressure of the gas? P2 = P1V1T2 / V2 T1 P2 = [15.8 dm³] [ 101.3 Kpa] [291K] [8.7 dm³] [298 K] P2 = 179.64 Kpa A sample of neon gas used in a neon sign has a volume of 15 L at STP. What is the volume (L) of the neon gas at 2.0 atm and –25°C? (6.81L)  Problem Two grams of oxygen gas were confined in a 2 litter vessel by a pressure of 1.21 atm. What is the temperature of this gas by 0 C ? (198.6 0C) 5.75 grm of a gas occupy volume of 3.4 litter at temperature of 50 C 0 and pressure of 0.94 atm. What is its molecular weight ? (47.91 g) Molly admires her red balloon, which has a volume of 2.0 liters at sea level (1.0 atm). A clown catches her eye, and she lets go of the balloon. The red balloon goes up and up until the pressure around it is 0.80 atm. Assuming isothermal conditions, what is the new volume of Molly's red balloon? (2.5 L) Thank you! Do you have any questions?