CHE 120 Homework Assignment Week 10 Lecture 19: Energy Forms and Conversion Problem 1: Based on the questions asked during the exam, let's review the following basics for CHE students. a) Write the chemical formulas for the following hydrocarbons: methane, ethane, propane, n-butane, n- pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane. (5 points) b) Convert the following daily-life temperature into absolute temperature. If the critical temperature of CO2 is Tc = 31 °C, calculate the reduced pressure T₁ = T/Tc (3 points) i. 0 °F, 100 °F, 100 °C to Rankine °R, T₁ =? ii. 0 °F, 100 °F, 100 °C to Kelvin °K, Tr. =? iii. Are the T values calculated the same in (i) and (ii)? c) Convert 0 psig to psia, ATA (absolute pressure in atm), mmHg-absolute (2 points) Problem 2: (Basic concepts, heat units, and their conversions) A seasonal power plant uses natural gas as fuel to generate electric power in the summer. The size of the power plant is 200 megawatts, and it operates between 10 am - 5 pm at full power. The heating value of the natural gas is 1000 BTU/SCF. The efficiency of converting thermal energy to electric power is n = 30%. a. Calculate the daily electricity generation, E, in joules (5 points) b. Calculate the daily fuel consumption, Vnatgas, in BCF and fuel cost. You must consider the conversion efficiency, n, given above. (5 points) c. Calculate the daily fuel cost, C, in $, using gas price $3/MMBTU d. Calculate the daily CO2 and water vapor discharges in pounds, assuming the natural gas consists of 100% methane. (5 points) Exhaust Heat Qheat CO₂ mco2 Natural Gas Power Plant Vnatgas H₂O MH20 E Electricity CHE 120-Spring2024-Chang 1 CHE 120 Homework Assignment Week 10 Lecture 19: Energy Forms and Conversion Problem 3: Textbook Problem 9.2.2 *9.2.2. A gas is contained in a horizontal piston-cylinder apparatus at a pressure of 350 kPa and a volume of 0.02 m³. Determine the work done by the piston on the gas if the cylinder volume is increased to 0.15 m³ through heating. Assume the pressure of the gas remains constant throughout the process, and that the process is ideal. a) The pressure is constant p = 350 kPa during the expansion process as described in the problem. Calculate the work done, Wexp. (5 points) b) The piston is next slowly pushed back so the volume is reduced from 0.15 m³ to its original volume V = 0.02 m³. During this compression process, the cylinder is kept at a constant temperature T = 375 K. The starting pressure is 350 kPa. Does the pressure remain constant during the compression process? Calculate the work done, Wcomp. (5 points) Problem 4: Textbook Problem 9.2.4 *9.2.4. What is the potential energy in joules of a 12 kg mass 25 m above a datum plane? a) Calculate the potential energy (PE) at h = 25 m. Use an average gravitational acceleration g = 9.81 m/s². (5 points) b) If the same object falls to the datum plane where h = 0 from the height of 25 m, calculate the İ. The potential energy of the object (PE), using the same datum. (2 points) ii. The kinetic energy of the object (KE). (3 points) iii. The velocity of the object v in m/s. (5 points) CHE 120-Spring2024-Chang 2 CHE 120 Homework Assignment Week 10 Lecture 20: Heat, Temperature and Heat Capacity Problem 5: Three objects have different masses, specific heat capacities and temperatures, as shown in the following diagram. We can assume that the specific heat capacities of the three objects are temperature-independent. a) Calculate the heat released or gained for each object if the temperature of the object is changed to 25°C (5 points) b) If the three objects are put together in a perfectly insulated container, the temperature inside the container will reach an equilibrium temperature T. c) Calculate the equilibrium temperature Te (5 points) d) Calculate the net heat gain or loss of each object, Q1, Q2, Q3 (5 points) m₁ = : 1 kg Cp1 = 920 J/kg-K T₂ = 160 °C = m3 = 3 kg Cp2 = 125 J/kg-K m₁ = 1 kg Cp1 920 J/kg-K T =? °C m3 = 3 kg m2 = : 2 kg T3 = 50 °C m2 = : 2 kg Cp2 = 125 J/kg-K T =? °C = Cp2 500 J/kg-K Cp2 = 500 J/kg-K T =?°C T₂ = -40 °C CHE 120-Spring2024-Chang 3