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Internal Energy

Internal energy is the total energy contained by a thermodynamic system. It is the energy required to create the system but remove the energy to displace the system’s surroundings, any energy connected with a move as a whole. The internal energy of a system can be changed by heating or cooling the system. The first law of thermodynamics states that an increase in internal energy is equal to the total heat added and work done by the surroundings.Therefore if a system is isolated, the internal energy cannot change.

Internal energy is a state function of a system because its value depends only on the current state of the system and not on the path taken or process underdone to arrive at the state. It is an extensive quantity. The SI unit of internal energy is a joule (J). Specific internal energy is the internal energy per unit of mass of the system in question.
Internal energy can be calculated by:

U= U_pot+ U_kin

And the change in internal energy is

∆U=Q+ W_mech+ W_extra

Categories within Internal Energy

System Work

Postings: 45

Work is the energy transferred by a system to another.

First Law of Thermodynamics

Postings: 55

The first law of thermodynamics states that the internal energy of an isolated system will remain constant and the energy cannot be destroyed.

Analysis of Internal Energy Changes, Catalysts and pH

More modern fireworks replace potassium nitrate with potassium chlorate. The thermochemical equation for the decomposition of potassium chlorate is shown in Equation 1. Often a catalyst is added to speed up this reaction. Equation 1: 2KClO3(s) = 2KCl(s) + 3O2(g) ?H = -89.4 kJ mol-1 For reaction 1 draw a fully labelled diagr

Obtain a change in entropy of the universe.

Consider a thermally isolated system that consists of a body at temperature T1 and a large reservoir at temperature T2 > T1. The reservoir is sufficiently large so that its temperature does not change. The body has constant pressure heat capacity of Cp that does not vary with temperature. Please explain to me how to obtain t

Thermodynamics: Enthalpy Change

Hi, hope you can help. bond molar bond enthalpy/kj mol^-1 N-H 392 H-H 436 N=N (triple bond) 945 reaction 1: N2 (g) + 3H2 (g) = 2NH3(g) Use the molar bond enthalpies above to show the overall enthalpy change for reaction one is -93kj mol^-1 show a

Waves and oscillations

A sound source sends a sinusoidal sound wave of angular frequency 3000 rad / s and amplitude 12.0 nm through a tube of air. The internal radius of the tube is 2.00 cm. (a) What is the average rate at which mechanical energy is transported to the opposite end of the tube? If an identical wave and the original wave travel alon

Determining Solutions for Example Physics Problems

1. How many calories are needed to raise 500 grams of water from 25 degrees Celsius to 40 degrees Celsius? 2. Define the following terms: a. Internal energy b. Specific heat c. Entropy d. Temperature 3. Suppose a 1 meter long bar expands 0.5 centimeters when heated. By how much will a 100 meter long bar of the sam

Heat capacity of a 2d electron gas and of a 2d phonon gas.

What physical conditions lead electrons in a metal to form a degenerated Fermi gas? Show that the density of states for an ideal two-dimensional Fermi gas of particle with spin 1/2 and mass m that occupies area A is: g(E)=(A/2pi)(2m/h^2) Obtain a relationship between the number of electrons per unit area and the Fermi ene

Thermodynamic process problem

A The drawing refers to one mole of a monatomic ideal gas and shows a process that has four steps, two isobaric (A to B, C to D) and two isochoric (B to C, D to A). Complete the following table by calculating U, W, and Q (including the algebraic signs) for each of the four steps and for the whole process.

Heat and Thermodynamics: Change in internal energy.

A cylinder (cross section is 0.2m2) with a free moving piston is filled with gas. The piston is attached to a heavy weight W = 10000N. Outside the cylinder, the air is at 300K and 1 atm. Initially the gas is at 300K, then it is heated to 400K. The heat capacity of the gas under the constant pressure is 500J/K. If the length of

Global Management

Research Chevron (http://www.chevron.com). Using your research findings from the Library and the Internet, develop both an EFAS (External Factors Analysis Summary) table and an IFAS (Internal Factors Analysis Summary) table.

Heat and Thermodynamics:Entropy change in Isothermal process

One mole of an ideal gas is contained in a thermally insulated container that is connected to another container of equal volume that is initially evacuated. The valve connecting the two containers is now opened and the gas allowed to expand isothermally to fill both sides - new total volume is twice original volume. A) What i

Physics Problem- Calculating the Speed with Kinetic Friction

In the figure, two blocks are connected by a string across a pully. m1 sits at rest on a table. m1 = 3.4 kg. Use work and energy to find the speed of the m2 = 2.5 kg block just before it hits the floor in each of the following cases. * Distance between the floor and m2 = 1.5 (a) The table is frictionless. (b) The coef

Engine operating between two volumes of liquid

Two volumes V1 and V2 of the same incompressible liquid at temperatures T1 and T2 are mixed together in a thermally isolated container. When equilibrium is reached, the mixtures is at a temperature Tmix. If instead a reversible heat engine were operated between the two volumes of liquid until they reached the same temperature, s

Set of 11 questions: Heat and thermodynamics

Please see the attachment. 1. An engine is used to lift a 2700 kg truck to a height of 3.0 m at constant speed. In the lifting process, the engine received 3.3 x 10^5 J of heat from the fuel burned in its interior. What is the efficiency of the engine? (a) 0.19 (b) 0.24 (c) 0.29 (d) 0.34 (e) 0.39 2. A gasoline engin

Energy and work done by a gas system

An insulated cylinder closed at one end by a frictionless piston contains 20g of hydrogen gas at 30 degrees Celsius. This is heated to 40 degrees Celsius with the pressure kept constant at 1 bar and the volume increases by 7*10^-4 m^3. (The specific heat of H2 at constant pressure is 1.4*10^4 JKg^-1 K^-1). a) What is the wor

PV=nRT - Use of ideal gas law: Boling water from a wood slurry

In our course lab, our experiment required us to take wood fibers and mix them into a slurry in which that slurry was 65% water content. We then formed the slurry into a brick and placed it in a small electric lab press where variable hydraulic pressure and heat energy was applied to this wet wood brick. Using a thermocouple

Change in internal energy

What is the change in internal energy of a system that has 655 J of work done on it and gives off 515 J of heat? (in J)

Canonical Ensemble

Prove that k sum over r of P_r Log(P_r) for the canonical ensemble. See attached file.

Ideal Gases & Constant Heat Capacity

1. An ideal gas with Cp/Cv=1.5 where Cp and Cv are respectively the heat capacities at constant pressure and constant volume, is used as the working substance of a Carnot engine. The temp of the source is 600K and that of the sink is 300K. The volume of gas changes from 4 to 1 liter at the low temp and the pressure at the vol

Thermodynamics 1st Law

The following are first law problems in Thermodynamics: 1. The molar energy of a mono atomic gas which obeys van der waals equation is given by: E =(3/2)*RT - (a/V) where V is the molar volume at temperature T, and a is a constant. Initially one mole of the gas is at temperature T1 and occupies vol

Heat content or Btu value of water at various temperatures?

Help?? Where can I find the Btu value or heat content of water at various temperatures such as 50, 60, 70, 80, 90 & 100 degrees F? Say 1 lb of water. Is it also generally safe to say that if the water is in contact with another surface, that the water will give up its heat content so long as the adjoining mass is cooler th

Heat and Thermodynamics

1. You have a 16 oz cup of coffee at 180 degrees F. That is way too hot to drink. So you want to cool the coffee off and decide to add some cold water. You add 2 ounces of cold water at 40 degrees F. How much will the water you added heat up? How much will the coffee that you poured the water into cool down? 2. An ai