CHEM 150 PROBLEM SET 1PHASES OF MATTER

1. A sample containing 7.00 g of CH4(g) is placed in a certain empty vessel at 30C. Calculate the mass of CO2(g) that must be added to the same vessel at the same temperature so that the partial pressure of CO2 will be twice that of CH4.

2. A. Calculate the root-mean-square, average and most probable velocities of CH4(g) at 30C.

B. What is the molecular mass of a gas if the time it takes to travel through an orifice is twice as fast as that of CH4?

3. A. For oxygen at 25C and 1 atm, calculate the frequency of collisions per cubic meter per second and the mean free path. The collision diameter of O2(g) is 0.361 nm.

B. Repeat the calculations in A for the same temperature but a pressure of 2 atm.C. Repeat the calculations in A for the same pressure but a temperature of 50C.D. Which factor, pressure or temperature, affects the quantities sought more

significantly?

4. A. Employing the Kamerlingh-Onnes equation of state, calculate the compressibility factors of CO(g) at -50C and pressures of (a) 10 atm and (b) 100 atm.Virial coefficients of CO at -50C: A = 18.312 C x 105 =

17.900 B x 102 = -3.6878 D x 108 = -17.911

B. Using the Kamerlingh-Onnes equation, calculate the density of CO(g) at -50C and 100 atm. Compare this value with that calculated using the ideal gas law. Account for the discrepancy.

5. Which equation will yield a more non-ideal behavior for a sample of H2(g) that exhibits a molar volume of 250 mL at 0C: van der Waals equation of state or Kamerlingh-Onnes equation of state? Prove your answer.For H2: tc = -239.9C Pc = 12.8 atm

Virial coefficients at 0C:A B x 102 C x 105 D x 108

22.414 1.3638 0.7851 -1.206

6. Consider two parallel layers of NH3 gas, one of large area and stationary, and the other 10 cm2 in area and moving at a fixed distance of 1 x 10 -6 above the first. What force in dynes will be required to keep the upper layer moving with a velocity of 5 cm per sec when the pressure of the gas is 10 mmHg and the temperature is 27C? The molecular diameter of NH3 is 0.30 nm.

7. A steel ball of density 7.90 g/cc and 4 mm diameter takes 55 sec to fall a distance of 1 meter through a liquid of density 1.10 g/cc. Calculate the viscosity of the liquid in poises.

8. The surface tension of mercury at 0C is 480.3 dynes/cm while the density is 13.595 g/cc. What must be the radius of the glass capillary tube for Hg to exhibit a fall in height of 10.0 cm?

9. What type of cubic lattice does a crystal possess if the first order of reflections from a given crystal are observed at angles of 710’, 1012’ and 1230’?

10.CsBr crystallizes in a body-centered cubic lattice with an edge length of 4.287 Å. How many units of CsBr are present in the unit lattice? What is the density of CsBr at 20C?