Calculate Pc Vc and Tc for NH3 gas using the van der Waals p

Calculate P_c, V_c, and T_c for NH_3 gas using the van der Waals parameters (a, b) and compare to the values in a handbook or the Internet. A glass light bulb shell is sealed by a glassblower and one small tip is pulled out into a long narrow point with an entrance hole of about 1/8 in. diameter. The open bulb is weighed and found to weigh 46.345 g. Then the bulb is completely filled with water using an eye dropper with a thin tip and the filled bulb is found to have a mass of 237.93 g. Use the density of water at 20 degree C of 0.99821 g/cm^3 to find the internal volume of the bulb. The bulb is then aspirated to remove the water and dried in an oven. When dry and cool the bulb is reweighed and found to still be 46.345 g prior to filling it with about 5 mL of a volatile liquid. The bulb with this small amount of liquid is placed carefully into a 250 mL beaker of water, which is heated to a boil at exactly 100 degree C. After reaching equilibrium at this temperature and all evidence of liquid is gone the glass tip is sealed with a tiny drop of glue, the bulb is removed from the boiling water, carefully dried, and found to weigh 47.309 g. Assuming the pressure was 1 atm when the bulb was sealed, what is the estimated molecular weight and a possible compound that has a volatile liquid close to this molecular weight? Calculate the moles of gas collected over water in a 600 mL container at 756 mmHg pressure at 20 degree C given that the vapor pressure of water is 2.3388 kPa at 20 degree C

Solution

To match your current system, you plan on changing both the impeller and the operating speed. What
impeller diameter and pump speed should you specify so that it will operate at its best efficiency point
with a pump head and a flow rate as close as possible to 15 m and 7.5 Lpm respectively? Assume the
best efficiency point for the pump at the conditions in the table occurs at a volumetric flow rate of 20
Lpm.