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    Heat & Thermodynamics

    Thermodynamics is a branch of natural science concerned with heat and its relation to energy and work. It defines macroscopic variables, such as temperature, internal energy, entropy and pressure, which characterize materials and radiation. It explains how they are related and by what laws they change with time. Thermodynamics describes the average behavior of very large numbers of microscopic constituents. Its laws are derived from statistical mechanics.

    Thermodynamics can be applied to a wide variety of topics in science and engineering such as engines, phase transitions, chemical reactions, transport phenomena and black holes. The results of thermodynamic calculations are vital for many fields including, chemistry, chemical engineering, aerospace engineering, mechanical engineering, cell biology, bio-medical engineering and material science.

    Thermodynamics was developed out of the desire to increase the efficiency of early steam engines. In particularly, the French physicist Nicolas Leonard Sadi Carnot in 1824 who believed that the efficiency of heat engines was the key that could help France win the Napoleonic Wars. However, the Irish born British physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854.

    Initially, thermodynamics of heat engines were concerned mainly with the thermal properties of their working material, such as steam. This study was then linked to the study of energy transfers in chemical processes/ Chemical thermodynamics studies the role of entropy in chemical reactions. Statistical thermodynamics gave explanations of macroscopic thermodynamics by statistical predictions of the collective motion of particles based on the mechanics of their microscopic behavior.

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    BrainMass Categories within Heat & Thermodynamics


    Solutions: 277

    Temperature is a quantity which indicates how hot or cold a body is.


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    Gibbs free energy and chemical potential

    Focus Question: Consider a sample of CaO(s) at 298K and 1 atm. Does the Gibbs energy of the sample increase, decrease of remain the same if the temperature is raised to 350K? Does the Gibbs energy of the original sample increase, decrease of remain the same if the pressure is increased to 2 atm? Important formula 1. For a co

    Entropy change of mercury vaporization at different temperature

    1. Consider the system of 20g (0.1 mole) sample of liquid mercury at 1bar of pressure in an open beaker. Given the data below calculate the change in entropy of the universe to vaporize this sample at room temperature (25C). Normal boiling point of Hg is 356.7C. You may assume the heat capacities are constant over this temperat

    First and second law of thermodynamics

    1. For the following processes, state whether the driving force is the first or second law of thermodynamics. The systems are in italics and we are only interested in whether the properties of the system have changed. Explain your choice in 1-2 sentences. a. Warming up exercises when muscles are worked the cells "burn" more g

    Calculation of ammonia thermodynamic properties

    1. In the table below is the thermodynamic data for ammonia (http://en.wikipedia.org/wiki/Ammonia_%28data_page%29) use this data to solve the following problems for mole of ammonia (state any assumptions you made): a. What is the melting point at standard conditions for ammonia? Boling point is given -33.4C. Assume you have a

    1-st and 2-nd laws of Thermodynamics

    1. Solve both of the following problems a. A sample of an ideal gas has the following initial conditions V=15L, T=250K and P=1atm. It is compressed isothermally until the change in entropy is -5J/K. What are the final conditions? b. Calculate the change in entropy when 50g of 80C water is poured into 100g of 10C water. Assume

    Energy Transfer in Living Organisms

    -Define the laws of thermodynamics. Include an example to support your definition. -What is Gibbs free energy? What are consequences for a biochemical reaction when Gibbs free energy is negative? Explain the role of enzymes when Gibbs free energy is negative and when it is positive. -Adenosine triphosphate (ATP) has been ca

    Thermodynamics of a Helium Gas Filled Balloon

    A balloon is filled with helium gas at 20.0ºC at 1.0atm (1atm = 1.01x10^5 N/m^2).The volume of the balloon after filling is measured to be 8.50m^3. The helium is then heated at constant pressure until its temperature is 55.0ºC. What is the heat flow into the gas? (CP for an ideal gas is (5/2)R.)

    With temperature increase, how far will the alcohol column move in the tube?

    A tube 4.4 mm in diameter is run through the stopper of a sealed 8-liter container. The tube outside the container forms a U, then runs in a straight line with slope .015 with respect to horizontal. Alcohol is introduced into the tube, and fills the U, extending into the linear section of the tube. The end outside the container

    Calculating Elevation Based on Boiling Point: Barametric Formula

    See attached file for full description. It is found that a certain liquid boils at a temperature of 95 degrees Celcius at the top of a hill, whereas it boils at a temperature of 105 degrees C at the bottom. The latent heat is 1000 cal/mol. What is the approrimate height of the hill?

    Thermodynamic Equations for Beta and Kappa

    Suppose that Beta = (v-a)/T and kappa = 3(v-a)/4P Show that the equation of state is P^3/4 (v-a) = AT, Where a and A are constants. [attachment is copy of problem written with symbols]

    Heat flow through a window

    A glass window 0.60 cm thick measures 83 cm by 42 cm. How much heat flows through this window per minute if the inside and outside temperatures differ by 18°C? _______ kJ/min The conversions are confusing me.

    Thermodynamics: Cloud rises on encountering a mountain

    A cloud moving across the ocean at 2000 m (height) encounters a mountain range. As it rises to 3500 m, it undergoes adiabatic expansion from p=0.802 to 0.602 atm. If the initial temperature of the cloud is 288 K, will it rain or snow on the mountains? (Assume air to be an ideal gas with Cpm = 28.86 J/mol*K)

    Pressure excerted by a Fermi gas, at absolute zero

    Show that the pressure exerted by a Fermi gas at absolute zero is p = (2NEf)/(5V) where N is the total number of particles, Ef the fermi energy and V is the volume. ((If you need to use the relation for the mean energy <E> of particles obeying Fermi-Dirac statistics at absolute zero t

    Vibrations and Harmonic Oscillators

    i) Show that the thermodynamic properties of an assembly of N three-dimensional harmonic oscillators are the same as those of an assembly of 3N of on-dimensional oscillators. ii) In the Einstein model, each atom in a solid acts as a three-dimensional simple harmonic oscillator. An atom in a crystal of copper has a typical vib

    Thermodynamics: Mass Flow Rate of Steam

    A boiler takes fuel oil of specific gravity 0.81 and calorific value of 27912KJ/KG form a tank 6.0M in diameter. At the time of the maximum firing, the level of fuel oil in the tank is lowered 51mm in one hour, and the absolute boiler pressure is 1620Kpa. What is the mass flow rate of steam from the boiler in KG/HR Note:

    Comparing cost efficiency of two A/C units based on COP

    Consider a building whose annual air-conditioning load is estimated to be 120,000 kWh in an area where the unit cost of electricity is $.10/kWh. Two air conditioners are considered for the building. Air conditioner "A" has a seasonal average COP of 3.2 and cost $5500.00 to purchase and install. Air Conditioner "B" has a s

    Heating a Gas

    Heat required to raise 1 kg carbon dioxide from -100 degrees C to -50 degrees C. I arrived at an answer of 654,657 Joules. I used the following: CO2-solid spec heat = 815 J/kgC CO2-vapor spec heat = 2 J/kgC sublimation point of 573,100 J/kgC Q=CmT CmT(at

    Conceptual physics for mass

    Provide a formula and then solve so I can see how to do this type of problem. A block of iron is heated from 22 degrees celcius to 52 degrees celcius, absorbing 6,750j of thermal heat. What is the mass of the block? Solve for mass but need to see formula and how you did this so I can learn this.

    Physics Problem Set

    1. A loud speaker is placed between two observers who are 120m apart, along the line connecting them. If one observer records a sound level of 60.0dB and the other records a sound level of 90dB, how far is the speaker from each observer? a: 3.7, 116.3 b: 4.3, 115.7 c: 6.2, 113.8 d: 8.6, 111.4. 2. A room measures 3.0m by

    Heat Pump Problem

    A heat pump is a heat engine run in reverse. In winter it pumps heat from the cold air outside into the warmer air inside the building, maintaining the building at a comfortable temperature... a. If the outside temperature in winter is ... See attached file for full problem description.

    The coefficent

    The coefficent of thermal conductivity has the unit a. j/(mk) b. w/(mk) c. j(sk) d.w/(sk)

    Thermodynamics: Heated Rod

    At 6 degrees Celsius a metal rod is 1.5 m total length with half the length steel and the other half brass. The rod is heated to 150 degrees Celsius. What is the total change in length?

    Determine the Thrust Specific Fuel Consumption

    Determine the thrust specific fuel consumption (tsfc) for the following conditions for an jet engine in cruise setting altitude producing 10,200 lbf of thrust for a fuel flow of 0.1 kg/s. Express tsfc in units of lb/lbT/hr.

    Air flow speed

    The heating and airflow ducts to and from the room are circular 0.30m in diameter, the room is 3mx4.5x6m and the air flow needs to be changed every 12 minutes. Calculate the Air flow speed.