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How do you calculate the H+ activity coefficient?

e.g., Calculate the pH of water containing 0.10 M KCl at 25°C. [H+] = [OH−]. However, the ionic strength of 0.10 M KCl is 0.10 M. The activity coefficients of H+ and OH− in Table 7-1 are 0.83 and 0.76, respectively, when μ = 0.10 M.

Can activity coefficient be greater than 1?

While activity coefficients are one or less for ions in aqueous solution, activity coefficients for some other species, such as dissolved gases, may be greater than one.

Is activity coefficient dependent on concentration?

In general, the activity depends on any factor that alters the chemical potential. Such factors may include: concentration, temperature, pressure, interactions between chemical species, electric fields, etc.

How is activity coefficient calculated?

Activity coefficients may be determined experimentally by making measurements on non-ideal mixtures. Use may be made of Raoult’s law or Henry’s law to provide a value for an ideal mixture against which the experimental value may be compared to obtain the activity coefficient.

What is the activity coefficient of an ideal solution?

In solutions, the activity coefficient is a measure of how much a solution differs from an ideal solution—i.e., one in which the effectiveness of each molecule is equal to its theoretical effectiveness and thus the activity coefficient would be 1.

Is activity coefficient a constant?

It shows the results using a calculation based on Henry’s law (approximating ideal-dilution) and again with one based on Raoult’s law (approximating a pure substance). In both cases, the activity coefficient is not constant over the range of concentrations.

What is the significance of activity coefficient?

Having chosen to express the composition of a solution in terms of particular molecular species (without regard to the actual existence of these mole- cules), the activity coefficient gives us a simple empirical expression for the properties of this solution as compared with a perfect solution of the same composition.

What is fugacity and activity coefficient?

The real gas pressure and fugacity are related through the dimensionless fugacity coefficient φ. For an ideal gas, fugacity and pressure are equal and so φ = 1. For a gas, the activity is simply the fugacity divided by a reference pressure to give a dimensionless quantity.

How does ionic strength affect activity coefficient?

As the ionic strength of a solution increases, the activity coefficient (γ) of an ion decreases according to the Debye–Hückel limiting law, log γ = −0.509z2I1/2.

What does Fugacity mean?

vapor pressure

What are Fugacity models used for?

Multimedia fugacity models are utilized to study and predict the behaviour of chemicals in different environmental compartments. The models are formulated using the concept of fugacity, which was introduced by Gilbert N.

What are the uses of Fugacity?

The concept of fugacity, which is widely used in chemical processing calculations, has also been successfully applied to a variety of environmental simulations of the fate and transport of organic contaminants.

Can Fugacity be greater than pressure?

The fugacity of a gas is basically defined as its effective partial pressure. The fugacity applies only to real gases, which consequently gives more accurate computations of chemical equilibrium constants. In an ideal gas, the fugacity and pressure are equal.

Is Fugacity a pressure?

Fugacity is a measure of the “real” partial pressure or pressure of a gas in comparison to ideal gas. It is the effective partial pressure or pressure – a measure of thermodynamic activity.

What is the unit of fugacity coefficient?

The fugacity of a pure gas species, or that in a gaseous mixture, can be expressed in pressure units (bar, Pa).

How does chemical potential vary with temperature and pressure?

As previously stated, the value of the chemical potential of a substance depends not only upon temperature, but upon pressure as well. Moreover, the potential generally increases when the pressure increases.

Does chemical potential energy increase with temperature?

Yes, potential energy increases with increasing temperature for at least the following three reasons: At a higher temperature, more atoms/molecules are in excited electronic states. Higher electronic states correspond to greater potential energy. Potential Energy is -2 times Kinetic Energy.

Why does chemical potential increase with pressure?

As the system experiences an increase in pressure, the chemical potential will change, depending on the molar volume. Thus, in (a), the molar volume of the liquid is greater than that of the solid and hence, the increase in molar volume is greater for the liquid than for the solid.

Why does chemical potential vary with temperature?

Yes, the chemical potential is generally a function of temperature. As such, the chemical potential in the specific case of a Fermi gas is a function of temperature. In the Fermi gas, the chemical potential is “repelled” by the region of higher density of states as the temperature increases.

What does chemical potential depend on?

The key point is that, in general, the chemical potential depends on everything about the system. To give a simple example of such dependence, molecule type A could represent protons in solution (implying a certain pH), which would affect the energy required to add an acidic molecule of type B.

What is standard chemical potential?

The standard chemical potential, /(/mu/st/), of a pure substance in a given phase and at a given temperature is the chemical potential of the substance when it is in the standard state of the phase at this temperature and the standard pressure /(p/st/).

What is the physical significance of chemical potential?

Under the most common thermodynamic condition of constant temperature and pressure, chemical potential determines the stability of substances, such as chemical species, compounds, and solutions, and their tendency to chemically react to form new substances, to transform to new physical states, or to migrate from one …

What is the physical significance of chemical potential and fugacity?

We say that at equilibrium each species in a system has the same chemical potential in all phases. The fugacity of a species describes an effective partial pressure in the gas phase. At low pressure of the system the fugacity of a species tends to be equal to its partial pressure.

Is chemical potential positive or negative?

For classical concentrations – that is when n/nQ ≪ 1, the chemical potential of an ideal gas is always negative. We can better understand the chemical potential by looking at a system with a difference (or a gradient) in potential energy. The simplest example is a potential step.

How do you measure chemical potential?

You can measure its pressure directly with a barometer. You can measure its temperature directly with a thermometer. Can you measure its chemical potential directly with a “chemical potentiometer?” To be clear: You have to measure it directly.