Chapter 4 - Phases and Phase Equilibria Flashcards
What is standard molar volume
22.4 L
The volume of any one mole of gas at standard pressure and temperature
State some factors of ideal gases according to the kinetic molecular theory of gasses
Ideal gasses are small, in constant motion, have no attraction or repulsion. Collisions don’t slow them down
Kinetic Energy = 1/2 mv^2 increases proportional to temperature when K is constant
Ideal gasses have four properties: weight, pressure, volume temperature
What is the equation for the ideal gas law
PV = nRT where p is pressure in atm V is volume n is moles R is the universal gas constant 0.0821 T is temperature in kelvin
State avogadros law and equation
Volume of a gas is directly proportional to number of moles/particles in the gas
V/n = constant or V1/n1 = V2/n2
State the relationship between volume and temperature
When pressure and molecules remain constant, volume of the gas is proportional to its temperature
V initial/ V final = T initial / T final
State the relationship between temperature and pressure
Temperature is inversely proportional to number of molecules in the gas. As volume increases, pressure decreases
V = constant x 1/P or P initial x V initial = P final x V final
An ideal gas at 27 celsius and 380 torr occupies a volume of 492 cm^3. How many moles?
rearrange for n PV = nRT 380 / 760 = 0.5 atm 27 + 273 = 300K Volume = 0.492L n = PV / RT = 0.5 x 0.492 / 0.0821 x 300 n = 0.001 mol
What is the difference between ideal gases and real gases?
PV = nRT is ideal only
real gases are subject to intermolecular forces
real gases will act more ‘ideal’ at lower temperatures
ideal gasses exist when pressure is low and temperature is high
gases most water soluble at high pressure low temp
What are the three types of bonding of liquids
Dipole-dipole
dispersion/london
hydrogen bonds (where H covalently bonds to O, N and F
*liquids are not compressible like gasses
*the mixing of two liquids is called ‘miscibility’
Assume there is 1 mole of ideal gas at 20 degrees. What would happen to pressure when temperature increases to 60 degrees?
Pf = P x Tf/Ti
= P x (273+60)/(273+20)
= P (333/293)
To convert ice to water what needs to happen?
a. energy needs to be put into the system
b. a catalyst needs to be present
c. small particles must be present
d. energy must be given off by the system
we are increasing the temp in this reaction, increasing temp is increasing energy. Energy is given off, its used/required for the reaction
5 moles at 10cm with a temperature of 300K and pressure of 3atm is heated to 450K. What is the pressure now?
450/300 x 3 = 9/6 x 3 3: 300 ?: 450 *x1.5 so 3 + 1.5 = 4.5
300K temp and height x = 5cm, increases to 400K temp and height x = 6cm. How many molecules of gas escaped?
300/400 x 6/5 = 18/20 = 90% therefore 10% escaped
1 mole of gas expands from x = 5cm to x = 10cm from heat increase. How much work was done?
Pressure = 3atm
area = 50cm^2
W = P (Vf - Vi) P = 3 (50 x 10) - (50 x 5) P = 3 (0.5 - 0.25) P = 3 (0.25) = 75J
2 moles of ideal gas cases a cap to be 5cm, with a temp of T1, pressure of 1atm. Weight is added to the cap so that x2 = 4cm and pressure is 1.5atm. What is T2 in relation to T1?
↑ pressure ↑ temperature
T2 = T1 (P2V2/P1V1)
= T1 (1.5 x 0.04/1 x 0.05)
T2 = 6/5 T1
