chapter 10- Gasses

Gases are defined as substances that have no fixed shape and can expand to fill the volume of their container. In this chapter, we will explore the properties of gases, including pressure, volume, and temperature, and how they relate to one another through the gas laws.

the particles in gasses are very loosely spread apart resulting in them having low densities compared to liquids and solids, which allows them to be easily compressed and expanded. Gasses are loosely bonded because they are not held together by strong intermolecular forces, allowing them to move freely and occupy a larger volume than their liquid or solid counterparts, their bonds are held together with London dispersion forces. These forces are weak and temporary, which contributes to the high kinetic energy of gas particles, enabling them to overcome these interactions and move independently. (their high kinetic energy also is part of the reason for their ‘gaseous’ state for lack of a better word.)

This high kinetic energy is also what leads to the rapid diffusion of gases, as particles spread out and mix with other gases in their environment(meaning they can move wherever they please, relatively quickly.).


one of the variables for gas is pressure. pressure is the amount of the force exerted per unit area, and it plays a crucial role in determining the behavior of gases under various conditions.



main tenets of kinetic-molecular theory

  1. gasses consist of large numbers of molecules that are in continuous random motion,

  2. the combined volume of all the molecules is negligible relative to the total volume of the container where the the gas is contained.

  3. energy can be transferred between molecules during elastic collisions

  4. the average kinetic energy doesn’t change, regardless of energy change, and it is it’s Kelvin(k) temperature. (K = c+273)


conversions

one atmosphere is 760 mm of Hg(760 is also how many torrs are in one atmosphere. one atmosphere is equal to 101.3 kPa (kilopascals) or 14.7 psi (pounds per square inch), which serves as a standard reference point for measuring atmospheric pressure.



laws of gasses

  • charles’s law(V1/T1 = V2/T2)

    the volume of a fixed amount of gas is directly proportional to it’s absolute temperature. formula: directly proportional, V1/T1 = V2/T2


  • gay-lussac’s law (P1/T1 = P2/T2)

    when the volume and number of moles of a sample of a sample of gas are held constant, it’s pressure will decrease if the kelvin temperature is decreased. inversely proportional, formula: P1/T1 = P2/T2


  • boyle’s law(P x V = K, P1 x V1 = P2 x V2)

    the smaller the container or “volume”(V) a gas is in, the more likely the gas inside is to have a high pressure(P). directly proportional, formula: P x V = K, P1 x V1 = P2 x V2


  • avogadro’s principle(V1/m1 = V2/m2)

    if there are equal volumes of gasses at equal pressures and temperatures, then they have an equal amount of particles or moles. directly proportional, formula: V1/m1 = V2/m2


  • universal gas constant

    P V/m T = R (universal gas constant) so, P1 V1/m1 T1 = P2 V2/m2 T2 v

    The equation above can be written to help identify the type of problem a gas problem is. you can write the equation and eliminate each variable in order to identify the law required to solve a problem, rather than using each individual formula.