Whats equal about equilibrium

Does equilibrium mean that the amounts of reactants and products are equal  

Measure 20 ml of water in a graduated cylinder and pour it into a 100-mL beaker. Fill the graduated cylinder to the 20-mL mark. Place a glass tube in the graduated cylinder and another glass tube in the beaker. The tubes should reach the bottoms of the containers. 

Cover the open ends of both glass tubes with your index fingers. Simultaneously, transfer the water from the cylinder to the beaker, and from the beaker to the cylinder. 

Repeat the transfer process about 25 times. Record your observations. 

How can you explain your observations during the transfer process What does this tell you about the concept of equilibrium  

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Consider the equation AG = AG° + RT ln(g). What is the value of AG for a reaction at equilibrium What does Q equal at equilibrium At equilibrium, the previous equation reduces to AG° = -RT ln(A. When AG° > 0, what does it indicate about K When AG° < 0, what does it indicate about K When AG° = 0, what does it indicate about K AG predicts spontaneity for a reaction, whereas AG° predicts the equilibrium position. Explain what this statement means. Under what conditions can you use AG° to determine the spontaneity of a reaction ... 

We have just learned that the concentrations of reactants and products are not equal at equilibrium rather, it is the rates of the forward and reverse reactions that are equal. But what about the concentrations What can we know about them The equilibrium constant (Keq) a way to quantify the relative concentrations of the reactants and products at equilibrium. Consider the generic chemical reaction ... 

Now what about approaching the equilibrium state by starting with hydrogen and oxygen Let us start with 1 mole of hydrogen and mole of oxygen and allow the reaction to attain equilibrium at 2273°K and a total pressure equal to one atmosphere. At equilibrium we find present 0.994 mole of water, 0.006 mole of H-, and 0.003 mole of 02. This can be summarized as follows ... 

A liquid solution may be separated into its constituents by crystallising out either pure solvent or pure solute, the latter process occurring only with saturated solutions. (At one special temperature, called the cryohydric temperature, both solvent and solute crystallise out side by side in unchanging proportions.) We now consider what happens when a small quantity of solute is separated from or taken up by the saturated solution by reversible processes. Let the saturated solution, with excess of solute, be placed in a cylinder closed below by a semipermeable septum, and the w7hole immersed in pure solvent. The system is in equilibrium if a pressure P, equal to the osmotic pressure of the saturated solution when the free surface of the pure solvent is under atmospheric pressure, is applied to the solution. Dissolution or precipitation of solute can now be brought about by an infinitesimal decrease or increase of the external pressure, and the processes are therefore reversible. If the infinitesimal pressure difference is maintained, and the process conducted so slowly that all changes are isothermal, the heat absorbed when a mol of solute passes into a solution kept always infinitely... 

The mechanism in Scheme 15 suggests the rapid formation of an intermediate that is cis about the central (3-methine bond, which leads eventually to the ring-closed form but which can also re-form the state as the equilibrium concentration depletes. Scheme 16 is based on the fact that two possible conformers for the merocyanine have been identified (TTC and TTT) [36] and these may have different ground-state recovery times, but TTC and TTT generate the closed form with equal efficiency. Both of these schemes have merit and both have possible flaws however, what is clear is that there is no triplet-state involvement and that the bleaching reaction generates the spiropyran closed form essentially within 1.5 nsec. 

One word about the Gibbs energies of adsorption. In equilibrium the molar Gibbs energy of adsorption is zero AadGm = /P — pT 0. The reason is simple. In equilibrium and for constant P and T the chemical potential of the molecules in the gas phase n9 is equal to the chemical potential of adsorbed molecules /P. What is not zero is the standard Gibbs energy of adsorption... 

What about solids and liquids Pure liquid and solid concentrations do not vary significantly in chemical processes, and their concentrations are always equal to their standard concentrations (usually one). So pure liquids and solids are omitted from equilibrium expressions. Of course, aqueous species are always included in the equilibrium expression. 

Up to this point, the focus has been on the effect of the oxygen partial pressure on the majority defects, that is, Vq and n under reducing conditions, (Vm and p under oxidizing conditions, and so forth). What about the electron holes and the metal vacancies in that region, the so-called minority defects To answer this question, it is important to appreciate that at equilibrium Eqs. (6.23) to (6.26) have to be satisfied at all times. For example, equilibrium dictates that at all times and under all circumstances the product [Vo][V"] has to be remain a constant equal to A,. And since it was just established that in the low oxygen pressure region [Eq. (6.29)] ... 

From the pH, you could calculate [H+j. Then, remember that for every mole per liter of H+ ion there must be an equal concentration of F ion. That means you know two of the variables in the expression. What about the third, [HF] The concentration of HF at equilibrium is equal to the initial concentration of the acid (0.1 OOM) minus the moles per liter of HF that dissociated, which is equal to ([H+]). 

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