Unit 5 Flashcards
Pressure
-force exerted per unit area as gas molecules strike surfaces around them
-how much exerted by gas sample depends on number of gas particles in a given volume
-fewer gas particles, lower total force exerted per unit area and lower the pressure
properties of gases
-gases expand to fill any space available
-all gases have low density(g/L)
-volume of a as changes dramatically with a change in pressure or temperature
-volume, pressure and temperature are interrelated for a particular mass of gas
millimeters of mercury/torr
-atmospheric pressure can support a column of mercury that is 760. mm high in barometer
-1mm Hg=1 torr
atmospheres(atm)
-average pressure at sea level
-1atm=760. mm Hg
pascal(Pa)
-SI unit of pressure
-1atm=101,300 Pa
kilopascals
-1atm=101.3 kPa
pounds per square inch(psi)
-measure of force per unit area
-1atm=14.7 psi
standard atmospheric pressure
- mm Hg = 760. torr = 1 atm = 101.3 kPa = 14.7 psi
Boyle’s Law
-inverse relationship between pressure and volume (T-temperature and n-amount of gas molecules constant)
volume vs. pressure
-as volume of gas sample decreases, gas molecules collide with surrounding surfaces more frequently, resulting in greater pressure
Charle’s Law (Volume and Temperature)
gases expand when heated decreasing density of gas
relationship between gas and temperature
-direct relationship as long as temperature is measured in kelvins
when temperature of gas increases, gas particles move faster
-collisions with the walls are more frequent and the force exerted with each collision greater
-only way for pressure(force per unit area) to remain constant is for the gas to occupy a larger volume so that collisions are less frequent and occur over a larger area
Charles Law expressed
-V1/T1=V2/T2
-V1 and T1 initial volume and temperature
at constant temperature
-volume occupied by a fixed mass of gas is inversely proportional to its pressure
Boyle’s law expressed
P1V1=P2V2
-P1 and V1 are initial pressure
Avogadro’s Law(amount in moles and volume)
-relationship between volume and number of moles is linear
-extrapolation to zero moles shows zero volume
when amount of gas in a sample increases at constant T and P
-its volume increases in direct proportion because the greater number of gas particles fill more space
Avogadro’s law expressed
V1/N1=V2/N2
celsius to kelvin
C+273=Kelvin
Gay-Lussac’s Law(Pressure and Temperature)
-if gas is contained in container, as kelvin temperature increases, pressure increases
-direct relationship
-volume held constant
Gay-Lussac’s law expressed
P1/T1=P2/T2