Basil has invested R16 497 000 in a family restaurant and he wants total sales revenue of 10% on his investment in the year to come.The restaurant has 100 seats and serves lunch and dinner 6 days a week for 52 weeks a year.From past experience Basil has learnt that lunch can be estimated at … Read more
Consider a block of concrete weighing 1 kg. (a) How far must it fall to change its potential energy by 1 kJ? (b) What would be the value of its velocity at that stage? A block of copper weighing 0.2 kg with an initial temperature of 400 K is dropped into 4 kg of water … Read more
In the preceding problem, suppose that the copper block is dropped into the water from a height of 50 m. Assuming no loss of water from the tank, what is the change in internal energy of the block? In the following take CV = 5 and CP = 7 cal/mol-K for nitrogen gas: (a) Five moles … Read more
A 700 kg piston is initially held in place by a removable latch above a vertical cylinder. The cylinder has an area of 0.1 m2; the volume of the gas within the cylinder initially is 0.1 m3 at a pressure of 10 bar. The working fluid may be assumed to obey the ideal gas equation of … Read more
A 700 kg piston is initially held in place by a removable latch inside a horizontal cylinder. The totally frictionless cylinder (assume no viscous dissipation from the gas also) has an area of 0.1 m2; the volume of the gas on the left of the piston is initially 0.1 m3 at a pressure of 8 bars. … Read more
A particular bubble cap distillation column for methanol + water has 12 trays numbered from top to bottom. Each tray is composed of 4 kg of materials and holds 1 kg of liquid. The heat capacity of the tray materials is 6 J/g-K and the heat capacity of the liquid is 84 J/mol-K = 3.4 … Read more
A vapor stream of wt fractions 45% H2O, 40% benzene, 15% acetone flows at 90°C and 1 bar into a condenser at 100 kg/h. The stream is condensed and forms two liquid phases. The water and benzene can be considered to be totally immiscible in one another. The acetone partitions between the benzene and water … Read more
Acetone (A) is reacted in the liquid phase over a heterogeneous acid catalyst to form mesityl oxide (MO) and water (W) at 80°C and 0.25 MPa. The reaction is . Conversion is to be 80%. The heat capacity of mesityl oxide has been estimated to be CPL (J/mol-K) = 131.16 + 0.2710T(K), CPV (J/mol-K) = 72.429 + … Read more
Dimethyl ether (DME) synthesis provides a simple prototype of many petrochemical processes. Ten tonnes (10,000 kg) per hour of methanol are fed at 25°C. The entire process operates at roughly 10 bar. It is 50% converted to DME and water at 250°C. The reactor effluent is cooled to 75°C and sent to a distillation column … Read more
The Arrhenius model of global warming constitutes a very large composite system.3 It assumes that a layer of gases in the atmosphere (A) absorbs infrared radiation from the Earth’s surface and re-emits it, with equal amounts going off into space or back to the Earth’s surface; 240 W/m2 of the solar energy reaching the Earth’s … Read more
