872

Physics Heat & Thermodynamics Level: High School

The heat capacity of aluminum can be described by : Cp = 20.67 + (12.38 x 10 to the negative 3) T J/mol K

(a) How much heat is necessary to heat 10.00 g of AL from 25 degrees Celsius to 535 degrees Celsius .

(b) list a least two assumptions implicit in your calculations of part (a)




871

Physics Properties Of Matter Level: High School

Gases

The root mean square speed of O2 molecule at 25 degree Celsius is 480 m/sec

(a) Predict the rms speed of CO2 molecules at 25 degrees Celsius

(b) To what temperature must the CO2 sample be changed to double its rms speed .




870

Physics Heat & Thermodynamics Level: High School

Give definitions of Cv and Cp by appropriate partial derivatives and operationally (ie , how do they work and what do they describe ?)



869

Physics Heat & Thermodynamics Level: High School

The Dieterici equation of state for real (non-ideal) gases may be written as

P = RT/V-x (-y/rv)/ (e) for n = 1 mole

What characteristics of the gas molecules would you expect the Dieterici constant x and y to be related to ? Explain in terms of the assumptions of the kinetic molecular theory ?




868

Physics Heat & Thermodynamics Level: High School

A volume of 50.0 liters of oxygen at 10 C and an absolute pressure of 1.88 atm is compressed to 36.6 liters , and at the same time the temperature is raised to 80 C . What will the absolute pressure be now ?



867

Physics Heat & Thermodynamics Level: High School

Calorimetry

Calculate the latent heat of fusion of ice from the following data for ice at 0 C added to water in a calorimeter . (results to 3 sing figs).

Specific heat of calorimeter 0.100 cal (gm C)

Mass of calorimeter 70.0 gm

Mass of calorimeter plus water 507.0 gm

Mass of ice added 169.0 gm

Initial temperature of plus calorimeter 40.0 C

Final temperature of the mixture 7.0 C




866

Physics Heat & Thermodynamics Level: High School

Thermal Expansion

A steel bar 115 mm long has a cross –sectional area of 145 mm2 . when its temperature is increased by 25 C , it will expand (lengthen)by a certain small amount , change (triangle ) L . What stretching force , F , would need to be applied to this same change in length , without any change in temperature . For steel Y = 20 x 10 (to the tenth power) N/m^2 .



865

Physics Heat & Thermodynamics Level: High School

Carnot’s Engine

An engine operates at half its theoretical (carnot) efficiency between 545 C and 310 C. What is the efficiency of the engine ?



864

Physics Heat & Thermodynamics Level: High School

To maintain the temperature inside a house at 26 degree C , the power consumption of the electric baseboard heaters is 10 kW on a day when the outside temperature is -9 degrees C . At what rate does this house contribute to the increase in the entropy of the universe ? Answer in units of W/K .



863

Physics Heat & Thermodynamics Level: High School

A refrigerator operator will Carnot efficiency between temperatures -4.8 degrees C and 33.3 degree C . What is the coefficient of performance ?



862

Physics Heat & Thermodynamics Level: High School

A heat pump has a coefficient of performance of 3.82 . If the heat pump absorbs 20cal of heat from the cold outdoors in each cycle , find the heat expelled to the warm indoors . Answer in units of cal .



861

Physics Heat & Thermodynamics Level: High School

A mass of 1.67 kg of chilled water at 0 degreesC is placed in a freezer which is kept at -19.7 degrees C . The freezer works as a Carnot engine , cice = 2.09 kJ/kg x degreesC and seawater = 4.186 kJ/kg degree C . Approximately how much electric energy is needed to operate the compressor to cool this water to -19.7 degreeC if the room temperature is maintained at 29.2 degreeC ? Answer in units of kJ .



860

Physics Heat & Thermodynamics Level: High School

Calculate the change in entropy of 3.47 mol of an ideal gas that undergoes a free expansion to 4.89 times its initial volume . Answer in units of J/K .



859

Physics Heat & Thermodynamics Level: High School

A solid substance that has a latent heat of fusion 21.6 kJ/kg melts at a temperature 302 degree C . Calculate the change in entropy that occurs when 0.483 kg of this substance is melted . Answer in units of J/K .



858

Physics Heat & Thermodynamics Level: High School

Calculate the change in entropy of 149 g of water heated slowly from 8.5 degreeC to 91.5 degree C . Answer in units of J/K .

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