Hydrogen fluoride equilibrium concentration

The bond dissociation energy of the hydrogen-fluorine bond in HF is so great that the above equilibrium lies to the left and hydrogen fluoride is a weak acid in dilute aqueous solution. In more concentrated solution, however, a second equilibrium reaction becomes important with the fluoride ion forming the complex ion HFJ. The relevant equilibria are ... 

Add the energies of propane and fluorine atom (at left (the reactants), and then the energies of 1-propyl radica (or 2-propyl radical) and hydrogen fluoride (th( products). Are these reactions exothermic or endothermic If the former, then calculate the relative concentrations 0 1-propyl radical and 2-propyl radical that would exist ii an equilibrium mixture at 298 K. Use equation (1). 

Figure 4.21 The equilibrium concentrations of HF in a mixture with H20 for the reduction of uranium oxide by hydrogen fluoride versus temperature.

Apparent photosynthetic rates in plants subjected to SO2 or NO exposures with constant pollutant concentrations, as illustrated in Figure 1, characteristically dropped rapidly upon initiation of treatment to new depressed equilibrium levels which could be maintained for several ho irs. Hydrogen fluoride, conversely, caused CO2 uptake rates to decline more gradually during fumigation. Chlorine, O3 and NO2 exposures induced inhibition rate responses which were intermediate between these... 

In Example 6.3 we were able to solve for the unknown by taking the square root of both sides of the equation. However, this situation is not very common, so we must now consider a more typical problem. Suppose that for a synthesis of hydrogen fluoride from hydrogen and fluorine, 3.000 moles of H2 and 6.000 moles of F2 are mixed in a 3.000-liter flask. The equilibrium constant for the synthesis reaction at this temperature is 1.15 X 102. We calculate the equilibrium concentration of each component as follows ... 

In dilute solutions and at neutral pH, dissolved fluorides are usually present as the fluoride ion (F ). As pH decreases, the proportion of F decreases, while hydrogen fluoride (HF ) and nondissociated hydrogen fluoride increase. Levels of nondissociated hydrogen fluoride also increase in concentrated solutions. In seawater, fluorides exist in equilibrium. Calcium carbonate precipitation dominates the removal of dissolved fluoride from seawater. The next most important removal mechanism is incorporation into calcium phosphates. Undissolved fluoride... 

M NH4NO3 with the total ionic strength maintained at (0.01 + 0.001) M. The experiments are described in detail, and the response of the fluoride electrode in different solutions and at different temperatures is discussed. Thorium fluoride equilibrium data (free fluoride molar concentrations and total molar concentrations of fluoride, hydrogen, and thorium) at 5, 25, and 45°C are presented in tabular form. 

Assume that the reaction for the formation of gaseous hydrogen fluoride from hydrogen and fluorine has an equilibrium constant of 1.15 X 10 at a certain temperature. In a particular experiment, 3.000 mol of each component was added to a 1.500-L flask. Calculate the equilibrium concentrations of all species. 

C. Concentrations were in moles per 1000 g of liquid HF, i.e., molalities. The specific conductance L was derived from Lmeasured l-soivent- According to these authors, this expression did not represent the actual relationship because of interaction between the solvent and solute. A large part of the solvent conductance was attributed to traces of water and salts. Water was described as a strong electrolyte in liquid hydrogen fluoride, and also as a strong base therefore, it will interfere with the acid-base equilibrium under examination. 

When a base is added to the hydrofluoric acid/fluoride ion buffer system, the added OH ions react with H+ ions to form water. This decreases the concentration of hydrogen ions and the equilibrium shifts to the right to replace the H ions. 

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