CHAPTER IINTRODUCTION

1.1 BackgroundThe most common use of an equation of state is a state in predicting the gas and liquid. One of the simplest equation of state is in the use of the ideal gas law, which is quite accurate in predicting the state of the gas at low pressure and high temperature. But this equation becomes increasingly inaccurate at higher pressures and temperatures are even lower, and failed to predict condensation from a gas to a liquid. Nevertheless, a number of more accurate equations of state have been developed for a wide range of gases and liquids. Currently, there is no single equation of state that can accurately predict the properties of all substances in all conditions. In addition to predicting the behavior of gases and liquids, there are also several equations of state in predicting the volume of solids, including solids transition from one crystalline state to another crystalline state. There is also the equations that model the interior of stars, including neutron stars. The concept is also related is the perfect fluid in the equation of state used in cosmology.When the system is in equilibrium under specified conditions, is called the bound state ( or state of the system ). To a certain thermodynamic state, many of the properties of the specified system. Properties that do not depend on the path where the state system was formed, called the state function of the system. The remainder of this section considers only property, which is a state function. Minimum number of properties that must be specified to explain the circumstances of a particular system is determined by the Gibbs phase law. Usually one is dealing with the property system larger than the minimum amount. Development of the relationship between the properties of different possible circumstances.

1.2 Problem FormulationBased on the above, as for the formulation of the problem as follows:1.2.1 What sense of Intensive and Extensive Variables?1.2.2 What is the sense of Equation circumstances?1.2.3 What is the sense of the ideal gas equation of state?1.2.4 What is the sense of real gas equation of state?1.2.5 How does the surface of p - V - T on ideal gas?1.2.6 How does the surface of p - V - T on a real gas?

1.3 ObjectivesBased on the above formulation of the issue, as for its purpose as follows:1.3.1 Students can explain the meaning of Intensive and Extensive Variables1.3.2 Students can explain the meaning of the equation of state1.3.3 Students can explain the notion of an ideal gas equation of state1.3.4 Students can explain the meaning of a real gas equation of state1.3.5 Students can explain how the ideal gas PVT surface1.3.6 Students can explain how the gas PVT surface estate

1.4 BenefitsAs for some of the benefit is expected to authors are:1.4.1 for AuthorsTask of this paper can be used as an ingredient as well as evaluation of the author in making papers, and can add new knowledge about what the equation of state.1.4.2. for ReadersTo add new knowledge, about what the theory of equation of state.

1.5 Method of WritingIn this paper, we use the method of writing a literature review writing methods.CHAPTER IIDISCUSSION

2.1 INTENSIVE AND EXTENSIVE VARIABLEEquation of state reveals differences in each system compared to other systems, so it must be determined by experiment or by molecular theory. Equation of state is not a theoretical the formula of thermodynamic, but rather is the result of the experiment. Equation that reveals the results of experiments with thermodynamics coordinate system measured as precisely as possible in a limited interval. In the equation of state is valid only in the interval of prices measured in the experiment. So the equation of state is valid only in the interval measure prices in experiment (Rapi, 2009).Before you will discuss the state of the system equations, there are some terms that will be used in the discussion of the equation of state. The term is intensive and extensive variables.Intensive variables are variables that do not depend on the mass or number of moles of the system. Examples of intensive variables are pressure (p) and temperature (T). While extensive variable is a variable that depends on the mass and number of moles of the system. Examples of extensive variables is the volume (V) and heat capacity (C). Extensive comparison between the mass of the system variable called the specific value of the variable.For example the ratio between the volume of the mass of the system is called the specific volume per unit mass or volume (v) and can be formulated ( Rapi, 2009) :v = V / mSfesifik volume is the inverse of density (), because density is defined = m / V = 1 / ( V / m ) = 1 / vSpecific volume and density are intensive variables. Comparison between the number of moles of extensive variable system called molal specific volume (v *) in the equation:

if there are n moles system with total mass m and M the molecular weight of the system molal specific:

2.2 EQUATION OF STATEThe state of a system can be expressed/described by thermodynamic variable, meaning that a system can be expressed with the pressure, volume, and with the other thermodynamic variables. The experimental results show no relationship between the variables in equilibrium. The relationship between pressure, volume and temperature specific so-called equation of state.In a state of thermodynamic equilibrium between the only 2-3 coordinate system to an independent variables. Gas equation mathematically expressed by the equation circumstances ( Rapi, 2009):f ( p,V,T ) = 0Explicitly expressed by the equation:P = p (V, T) in this case V and T are independent variables, while p is the dependent variable.V = V (p,T) in this case p and T are the independent variables, while V is the dependent variable.T = T (p,V) in this case p and V are independent variables, while T is the dependent variable.

2.3 IDEAL GAS EQUATION OF STATEOne of the simplest equation of state is in the use of the ideal gas law, which is quite accurate in predicting the state of the gas at low pressure and high temperature. But this equation becomes increasingly inaccurate at higher pressures and temperatures are even lower, and failed to predict condensation from a gas to a liquid. Nevertheless, a number of more accurate equations of state have been developed for a wide range of gases and liquids. Currently, there is no single equation of state that can accurately predict the properties of all substances in all conditions.Ideal gas is a gas that is idealized by men, in real ideal gas is not found in the earth's surface. To give an idea of the ideal gas state experts give good descriptions macroscopically and microscopically which will be discussed below.Macroscopically, ideal gas is a gas that meets or subject to equations Boyle - Gay Lussac, with the equation:

or p . V = RTWhere, P = gas pressure ( N/m2 )V = volume of gas ( m3 )n = number of moles ( mol )R = the universal gas constant ( R = 8.315 J / mol.K )T = absolute temperature of gas ( K )Microscopic, ideal gas illustrated with some basic assumptions are: A gas consists of particles - particles called molecules, with a very large number of molecules.Depends on the gas, then each molecule would consist of an atom or group of atoms. If the gas is an element or compound and is in a stable state, then we will review all of the molecules as the molecules are identical. The molecules move randomly obey Newton's laws of motion.The molecules move in all directions and with different rate. In calculating the properties of motion we assume that Newtonian mechanics can be used at the microscopic level. The total number of molecules is largeDirection and rate of movement of each molecule can change suddenly due to collisions with the walls or with other molecules. Each molecule of gas will follow a tortuous path for the collision. However, because the number of molecules we assume that a large number of collisions produced will retain overall distribution of molecular speed and randomness of movement. Molecular volume is very small compared to the volume occupied by the gas , the molecules are ignored.Although the number of molecules is very large but the molecules are unbelievably small. We know that the volume occupied by a gas can be changed through a range of great value with little difficulty, and that when a gas condenses the volume occupied by the liquid can be a thousand times smaller than the volume occupied by the gas. There is no significant force between the molecules except during collisions.The extent to which this assumption is true then a molecule will move with uniform velocity between collisions. Collisions between molecules, or molecules with the walls, the collision is elastic and occurs within a very short time.Collisions between molecules and between molecules with the walls of the container to maintain the conservation of momentum and conservation of kinetic energy will sustain. Because the collision time is negligible compared to the time spent by a molecule between collisions, the kinetic energy is converted into potential energy during the collision will be available once again as kinetic energy after such a short time so that we can ignore all of the energy exchange.Ideal gas equation is also obtained through experimental results with the following steps, the number of moles of gas n real ( CO2 ) altered the volume of gas pressure (p) was measured, experiments were performed at different temperatures. Value pV/T is computed and plotted on the ordinate and the abscissa p as shown in the figure below:

Figure 1 ( T3 > T2 > T1 )From the analysis of the curves in the figure above it can be concluded: The higher the temperature curve is a straight line. All curves intersect at low pressure in one point on the ordinate the value of pV / T = 8314.9 joules / kg - mole degree.Experiment as above was also carried out on other gases. The experimental results show at a given temperature all curves intersect at one point. It has a sense of limit comparisons pV / T for all the gas constant, and then given a notation with constant R is called the general, and mathematically given by the equation:

In the mks system, the value of R = 8.3145 103 joules / kg - mole degree . So at low pressure relationships between p,V, and T can be expressed by the equation :P V = n R T or pV = RT ( ideal gas equation )At low pressure above equation applies to all kinds of real gas, because the low pressure gas is considered to behave like a real ideal gas.2.4 REAL GAS EQUATION OF STATEIdeal gas laws which have been described is an apt description for all the gas was not so high pressure and temperatures far from the melting point. One of the real gas equation gas equation of state of Van der Walls were expressed with equation (Rapi, 2009):

Where a and b are constants that cost is different for each gas. If we compare, Van der Walls equation of state different from the equation of state for an ideal gas. In the Van der Walls equation of state at the pressure is still there a/v2 components embodying pressure caused by intermolecular forces are taken into account in the gas real gas. On the volume is still there b component that is part of the volume occupied by all molecules of gas, because the gas volume of real gas molecules is not negligible against the volume occupied by the gas.If large volumes of gas once, then a/v2 and b in the above equation can be neglected, so that the equation back into equation of state for a perfect gas.Another form of the equation is called the virial equation.

A, B,C, ..... is a function of temperature and are called virial coefficients. For a perfect gas = RT and B = C = D = ... = 0. Van Der Waals equation can be written in the form varial. Equation ( pV = nRT or PV = RT ) can be changed to :

the binomial formula,

So in the form virial equation to Van der Waals

In this case it is: A = RT ; RTB - B = a, C = RTb2.Beattie - Bridgman equation closely matches the experimental results for the region p, v and T are large. This equation is a modification of the virial equation.

Ao, a, Bo, B and C are constants of different values for different gases. A and b can be seen in Table 1 for each gas.table 1.Values of a and b for various gasZat a(n-m4)b(m3Kg-1m-1mol-1)

He3,441030,0234

H224,80,0266

O21380,0318

CO23660,0429

H2O5800,0319

Hg2920,0055

One can now sum up the difference between the real and the ideal gas as follows ( Tutor Vista , 2010) :

2.5 The surface of the p - V - T on Ideal GasOf the experiment, the values of the thermodynamic variables depend on each other. Relations are called the equation of state ( Anonymous, 2009).

Figure 1. Examples that prove the thermodynamic variables are relatedEquation of state shows the relationship between the three variables p,V, T. If the variables are plotted along three mutually perpendicular lines and the third line denote the pressure, volume, and temperature, the equation of state is defined as the surface is called the surface p-V-T. p-V-T surface for ideal gas is shown in the following figure.

Figure 1 . The surface of the p - V - T for an ideal gasEach equilibrium state of an ideal gas is shown by the dots on the surface of p-V-T or in other words each point on the diagram describes the equilibrium state p-V-T. Reversible process is a series of states of equilibrium, then on the surface of a line described as p-V-T. So, the lines on the surface of p-V-T describe a reversible process that served system ( Rapi, 2009).

(a)(b) TemperaturePressureVolumePressure(c) TemperatureVolume

Figure 2 . Projection surface p - V - T for an ideal gas Graph ( a) in the p-V diagram describing a process at constant temperature. This process is called the isotherm and the line on the pV diagram called isotherm line. Graph ( b ) in the p-T diagram describing a process at constant volume. This process is called isokhorik process. Graph ( c ) in the V-T diagram describing a process at constant pressure. This process is called isobaric process.2.6 The surface of the p - V - T on Real GasAt sufficiently low pressures, any true substance gas properties near perfect, but it will increasingly deviate from the perfect gas properties at high pressures and low temperatures. When the temperature is lowered and the pressure is increased, then any substance will change from gaseous phase into liquid phase or solid phase. Any substance that has a condition equation of state and although it is difficult to formulate a general equation form is mathematically, but still can express graphically based p-V-T surface.A pure substance or substances are in the gas phase at high temperature and low pressure. At the time of low temperatures and high pressures a transition to the liquid phase and solid phase. In this case the need to distinguish two kinds of real substance, a substance that closes and expands when it freezes.

In the diagram for the real gas p-V-T surface indicated the areas for the solid phase, liquid phase and gas phase, as well as areas koeksisistensi, the two phases are in equilibrium. In addition, there are also lines the triple point, where all three phases are common. Triple point of a substance is the temperature at which the price is solid, liquid and gas phases are at equilibrium.

Figure 9. Triple point in substance that closes and expands on freezingVapors and liquids in the area of koeksisistensi called saturated vapor and saturated liquid. By the saturated vapor pressure is called the vapor pressure. If the isothermal process continues after all the substance into a liquid, then one day arise crystals solids, namely in the area of solid liquid koeksisistensi. Pressure on the region remained constant. Koeksisistensi between solid and vapor phase may also occur, ie at high enough pressure. Liquid phase can not be at a lower temperature of the triple point or at a lower pressure than the pressure at the triple point. If it is lower than the pressure at the triple point, the substance may be the only solid and vapor phase only. With the exception of water, the water can occur anomalous events, where water can exist in liquid phase even though the temperature is lower than the temperature of the triple point.

CHAPTER IIICLOSING3.1 Conclusions3.1.1 Intensive And Extensive VariableIntensive variables are variables that do not depend on the mass or number of moles of the system. Examples of intensive variables are pressure (p) and temperature (T). While extensive variable is a variable that depends on the mass and number of moles of the system. Examples of extensive variables is the volume (V) and heat capacity (C).3.1.2 Equation Of StateThe state of a system can be expressed / described by thermodynamic variable, meaning that a system can be expressed with the pressure, volume, and with the other thermodynamic variables.3.1.3 Ideal Gas Equation Of StateIdeal gas is a gas that is idealized by men, in real ideal gas is not found in the earth's surface. To give an idea of the ideal gas state experts provide descriptions of both macroscopic and microscopic.3.1.4 Real Gas EquationIdeal gas laws which have been described is an apt description for all the gas was not so high pressure and temperatures far from the melting point. One of the real gas equation gas equation of state of Van der Walls.3.1.5 Surface p-V-T The Ideal GasEach equilibrium state of an ideal gas is shown by the dots on the surface of p-V-T or in other words each point on the diagram describes the equilibrium state p-V-T.

3.1.6 Surface p-V-T In Real GasIn the diagram for the real gas PVT surface indicated the areas for the solid phase, liquid phase and gas phase, as well as areas koeksisistensi, the two phases are in equilibrium. In addition, there are also lines the triple point, where all three phases are common. Triple point of a substance is the temperature at which the price is solid, liquid and gas phases are at equilibrium.3.2 SaranSetelah membaca makalah ini, penulis dapat memberi saran untuk mahasiswa, untuk lebih banyak membaca dan memahami tentang Persamaan Keadaan, agar nanti ketika menjadi seorang pendidik mampu menjelaskan tentang apa itu Persamaan Keadaan.

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