Ice Table Calculation
Ice Table Calculation - Related Videos
02:46
Calculating the Equilibrium Constant
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2020
The equilibrium constant for a reaction is calculated from the equilibrium concentrations (or pressures) of its reactants and products. If these concentrations are known, the calculation simply involves their substitution into the Kc expression. For example, gaseous nitrogen dioxide forms dinitrogen tetroxide according to this equation: When 0.10 mol NO2 is added to a 1.0-L flask at 25 °C, the concentration changes so that at equilibrium, [NO2] = 0.016 M and [N2O4] = 0.042 M. The value of the...
02:45
Calculating pH Changes in a Buffer Solution
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2020
A buffer can prevent a sudden drop or increase in the pH of a solution after the addition of a strong acid or base up to its buffering capacity; however, such addition of a strong acid or base does result in the slight pH change of the solution. The small pH change can be calculated by determining the resulting change in the concentration of buffer components, i.e., a weak acid and its conjugate base or vice versa. The concentrations obtained using these stoichiometric calculations can be used...
02:49
Calculating Standard Free Energy Changes
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2020
The free energy change for a reaction that occurs under the standard conditions of 1 bar pressure and at 298 K is called the standard free energy change. Since free energy is a state function, its value depends only on the conditions of the initial and final states of the system. A convenient and common approach to the calculation of free energy changes for physical and chemical reactions is by use of widely available compilations of standard state thermodynamic data. One method involves the...
01:12
Flow Table Test
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2024
The flow table test is an established method used to assess the workability of concrete, particularly useful for evaluating highly flowable concrete mixes. This test employs an apparatus that consists of a wooden board topped with a steel plate, collectively weighing 35 pounds. The board is connected to a base via a hinge and measures 27.6 inches on each side. Concrete is placed within a truncated cone mold that is 8 inches high with an 8-inch base diameter and a 5-inch top diameter. The...
02:05
Calculating Equilibrium Concentrations
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2020
Being able to calculate equilibrium concentrations is essential to many areas of science and technology—for example, in the formulation and dosing of pharmaceutical products. After a drug is ingested or injected, it is typically involved in several chemical equilibria that affect its ultimate concentration in the body system of interest. Knowledge of the quantitative aspects of these equilibria is required to compute a dosage amount that will solicit the desired therapeutic effect. A more...
FAQs
The stoichiometric coefficients determine how each concentration changes relative to the unknown shift, x. A reactant’s change is written as a decrease and a product’s as an increase, with the coefficient multiplying x. This preserves the reaction ratio while the system moves toward equilibrium, so the table connects reaction stoichiometry to the algebraic equilibrium expression.
Using one unknown change, usually x, keeps all equilibrium concentrations linked to the same reaction shift. Each expression must remain physically meaningful: concentrations cannot become negative, and the selected direction of change must match the signs assigned in the table. These checks help identify algebraic solutions that do not describe the chemical system.
The equilibrium constant expression is formed from the equilibrium concentrations, not simply from their initial values. Substituting the ICE-table expressions into that relationship produces an equation containing x. Solving it determines the extent of the shift required by the specified equilibrium constant, after which the resulting concentrations show how far the reaction proceeds.
Start with the reversible reaction and record the initial concentration of every relevant reactant and product. Next, write concentration changes using x and the reaction’s stoichiometric coefficients. Add the initial and change entries to obtain equilibrium expressions, substitute them into the equilibrium constant expression, and solve for x before calculating the final concentrations.
Check that every calculated concentration is physically meaningful and that the signs of the changes agree with the direction represented in the table. Also examine any assumption that a concentration change is negligible. If that assumption is not appropriate, retaining the x terms gives a more reliable equilibrium calculation rather than simplifying prematurely.
The method supports several equilibrium contexts, including acid-base reactions, solubility equilibria, and gas-phase systems. Although the chemical components differ, each application uses initial concentrations, stoichiometric changes, and equilibrium relationships to quantify the system’s final composition. This makes the approach useful for comparing how different reversible reactions distribute reactants and products at equilibrium.