Sodium hydroxide activity coefficient

The reduction potentials for the actinide elements ate shown in Figure 5 (12—14,17,20). These ate formal potentials, defined as the measured potentials corrected to unit concentration of the substances entering into the reactions they ate based on the hydrogen-ion-hydrogen couple taken as zero volts no corrections ate made for activity coefficients. The measured potentials were estabhshed by cell, equihbrium, and heat of reaction determinations. The potentials for acid solution were generally measured in 1 Af perchloric acid and for alkaline solution in 1 Af sodium hydroxide. Estimated values ate given in parentheses. 

For this calculation it is assumed that both the acid and the base are completely dissociated and the activity coefficients of the ions are unity in order to obtain the pH values during the course of the neutralisation of the strong acid and the strong base, or vice versa, at the laboratory temperature. For simplicity of calculation consider the titration of 100 mL of 1M hydrochloric acid with 1M sodium hydroxide solution. The pH of 1M hydrochloric acid is 0. When 50 mL of the 1M base have been added, 50 mL of unneutralised 1M acid will be present in a total volume of 150 mL. 

Substances typical of acids and bases are, respectively, HCl and NaOH. Hydrogen chloride dissolves in water with practically complete dissociation into hydrated protons and hydrated chloride ions. Sodium hydroxide dissolves in water to give a solution containing hydrated sodium ions and hydrated hydroxide ions. Table 3.6 gives values of the mean ionic activity coefficients, y , at different concentrations and indicates the pH values and those expected if the activity coefficients are assumed to be unity. 

The effect of the basicity of aldol condensation catalysts on their activity was thoroughly investigated by Malinowski et al. [372—379]. The observed linear dependence of the rate coefficients of several condensation reactions on the amount of sodium hydroxide contained in silica gel (Figs. 12 and 13) supported the view that the basic properties of this type of catalyst were actually the cause of its catalytic activity, though the alkali-free catalyst was not completely inactive. The amphoteric nature of the catalysis by silica gel, which can act also as an acid catalyst, was demonstrated [380]. By a stepwise addition of sodium acetate to a HN03-pretreated silica gel catalyst the original activity for acetaldehyde self-condensation was decreased to a minimum (when an equivalent amount of the base was added) by further addition of sodium acetate, the activity increased again because of the transition to a base... 

In a catholyte containing 100 g NaOH and 190 g NaCl per litre of solution there are 2.73 moles of NaOH and 3.55 moles of NaCl in 1000 grams of water (i. e. mNa+ = 6.28, wia- = 3.55 and moH- = 2.73). In order to calculate the activity coefficient of sodium hydroxide or of hydroxyl ions respectively the Debye-Huckel theory is applied according to this, the activity coefficient of... 

It will be found in the Table 8 that the mean activity coefficient of NaOH or rather the activity coefficient of hydroxyl ions in solutions of pure sodium hydroxide with an ionic strength fx = 6.28 (equal to the value of the molality, in this case) will be ... 

Reaction of ammonia with hypochlorite (to form chloramine, NH Cl) is a second-orderprocess ° jinvolvingeitherreaction of NH4 -l-OCl" or NH3-fHOCl it certainly does not involve NH3-I-OC1". Assuming the non-ionic mechanism, the rate coefficient at 25 °C, in 1 M sodium hydroxide sulution, is 6.2 x 10 1. mole" sec and the activation energy 2.5 kcal.mole" ... 

It has been assumed that the indicator acid was neutralized with sodium hydroxide. Furthermore, concentrations are employed instead of activities since the activity coefficients have values in the neighborhood of unity at the great dilutions involved. 

Table I. The Computation of the Activity Coefficients of Sodium Hydroxide From Cells Without Transference at 25°...

Fig. 2. Hitchcock Plot lot the Extrapolation of Activity Coefficient Ratios for Sodium Hydroxide.

Assuming that the lithium hydroxide solution has the same activity coefficient, 0.759, as sodium hydroxide gives, with equation (10), at 25°... 

From the temperature coefficient of the rate constant, the activation energy for the Claus reaction over the Chromosorb-A was determined to be 25.0 kcal/mole and for the sodium hydroxide-loaded Chromosorb-A it was about 15 kcal/mole. The apparent change in the slope of the Arrhenius plot might indicate some transition in the controlling mechanism. Over the cobalt-molybdena catalyst, the Claus reaction appeared to be diffusion-controlled with an activation energy of 5.5 kcal/mole (2). 

There is no change in the value of x, so we discontinue successive approximations at this point. We could have predicted this result from the small size of x from the first approximation. We now return to the successive approximation scheme for the activity coefficients. The ionic strength is the same as though the sodium acetate did not react, since every acetate ion that reacts is replace by a hydroxide ion. The ionic strength is / = O.lOOmolkg . By the Davies equation ... 

Literature data (Robinson and Stokes, 1959) for the activity and osmotic coefficients of potassium hydroxide and sodium hydroxide solutions, at 25 C, are listed in Table 2.4. The activity and osmotic coefficients of each of these alkali hydroxides have been fitted simultaneously using Eqs. (2.63) and (2.64), respectively (to keep the uncertainty in each point similar, a weight of has been used where X is the measured value). The fits obtained are illustrated in Figures 2.1 and 2.2. From these fits, the values obtained for the ion interaction parameters are... 

Table 2.4 Osmotic and activity coefficient data (Robinson and Stokes, 1959) for potassium and sodium hydroxide solutions at 25 °C.

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