One process for decaffeinating coffee uses carbon dioxide ( M=44.0 g/mol) at a molar density of about 14,0 mol/m3 and a temperature of about 60 . (a) Is CO2 a solid, liquid, gas, or supercritical fluid under those conditions? (b) The van der Waals constants for carbon dioxide are a=0.3658 Pa m6/mol2 and b=4.286105 m3/mol. Using the van der Waals equation, estimate pressure of CO2 at that temperature and density. `

The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about 0.20 W/m K and 0.020 W/m K, respectively, while other tissues inside the body have conductivities of about 0.50 W/m K. Assume that between the core region of the body and the skin sin face lies a skin layer of 1.0 mm, fat layer of 0.50 cm, and 3.2 cm of other tissues. (a) Find the R-factor for each of these layers, and the equivalent R-factor for all layers taken together, retaining two digits. (b) Find the rate of energy loss when the core temperature is 37C and the exterior temperature is 0C. Assume that both a protective layer of clothing and an insulating layer of unmoving air a absent, and a body area of 2.0 m2.

In 1993, the U.S. government instituted a requirement that all room air conditioners sold in the United States must have an energy efficiency ratio (EER) of 10 or higher. The EER is defined as the ratio of the cooling capacity of the air conditioner, measured in British thermal units per hour, or Btu/h, to its electrical power requirement in watts. (a) Convert the EER of 10.0 to dimensionless form, using the conversion 1 Btu = 1 055 J. (b) What is the appropriate name for this dimensionless quantity? (c) In the 1970s, it was common to find room air conditioners with EERs of 5 or lower. State how the operating costs compare for 10 000-Btu/h air conditioners with EERs of 5.00 and 10.0. Assume each air conditioner operates for 1 500 h during the summer in a city where electricity costs 17.0 per kWh.

In a 60 mm diameter cylindrical nuclear reactor fuel rod ė ü, 1 = 3.929 × 107 W / m3 uniformly distributed There is heat generation and the temperature distribution in continuous regime is given by the equation T = a + br2. Here, A = 650 ° C and b = -3.274 x 105 ° C in T (° C) and r (m) units. The properties of the rod k = 30 W / m. K, p = 1100 kg / m3 and cp = 800 J/ kg · K: (a) What is the heat conduction (W 7 m) from the unit length of the rod at r = 0 (axis) and r = mm (surface)? (b) Reactor power level suddenly ė lf ü is increased to 2 = 108 W / m3, at r = 0 andr= be What is the change (@T / at) with time? 30 mm the temperature will

According to the USDA, an average, \moderately active" college student needs to eat 2500 calories per day. These \calories" are actually kilocalories, or kcal; and, we prefer to use Joules (J) in geophysics. The conversion is 1 kcal = 4187 J. The average geothermal heat ux is 60 mW/m2. How large an area on Earth's surface releases the same amount of energy in one day as used by the average college student in a day?

(1a). Black body has emissivity value of 1, but in reality, the emissivity of real objects is less than 1. Why?e (1b). The tungsten sphere of 240 mm radius is at a temperature of 25°C. If the power radiated by sphere is 91 W, calculate its emissivity value? (1c).If the same sphere is enclosed in room whose walls are kept at -7°C, what is the net flow rate of energy out of the sphere in Watts (W)

The molar heat capacity at constant pressure of carbon dioxide is 29.14 J/K.mol. (a) What is the value of its molar heat capacity at constant volume? J/mol. 4 sig. (b) Calculate the change in enthalpy when 1 mole carbon dioxide is heated from 15°C (the temperature when the air is inhaled) to 37°C (blood temperature, the temperature in our lungs)? number normal format. (c) Calculate molar internal energy when carbon dioxide is heated from 19.16 °C (the temperature when the air is inhaled) to 37°C (blood temperature, the temperature in our lungs). normal format. J/mol 3 sig. number Click Save and Submit to save and submit. Click Save All Answers to save all answers. E R O El 5 G E O A J/K.mol. 4 sig. number H FO 1₂ Save All A 87°F ^!

Assume Lake Michigan contains 4.90 x 1012 m³ of water, and assume the water's density is that of water at 20°C and 1 atm. (a) How much energy (in J) is required to raise the temperature of that volume of water from 12.2°C to 24.4°C? 4.1E19 From the density of water and the volume, what is the mass of the water? What is specific heat? How is it related to the energy input, mass, and temperature change? Use it to solve for the energy. Be careful with units. J (b) How many years would it take to supply this amount of energy by using a power of 1,400 MW generated by an electric power plant? 926 How is power related to energy and time? Knowing the energy from part (a), can you find the time? Be careful with units. Make sure you convert the time in seconds to years. yr

A shipment from Earth to Mars contains a 50 gallon​ [gal] tank filled with an ideal gas. The molecular weight of the ideal gas is 15.9 grams per mole​ [g/mol]. NASA tells the astronauts on Mars that the tank and gas combined had an initial total mass of 5 kilograms​ [kg] and the pressure was 3 atmospheres​ [atm] before it left the Earth. During the​ trip, the temperature was kept constant at 20 degrees Celsius ​[°​C]. When it arrives on​ Mars, the astronauts check the sensors and discover the pressure is 2.2 atmospheres​ [atm] and the temperature is 20 degrees Celsius ​[°​C]. Based on this​ information, the astronauts determine that some of the gas leaked during shipment. Determine how much gas leaked from the tank in units of grams​ [g]. Gravity on Mars​ = 3.71 meters per second squared​[m/s2​].