Condensation molar heat

Now in principle each layer will have its own values of a, q, and v, and consequently the summation of Equation (2.11) cannot be carried out unless simplifying assumptions are made. Brunauer, Emmett and Teller made three such assumptions (a) that in all layers except the first the heat of adsorption is equal to the molar heat of condensation q, (b) that in all layers except the first the evaporation-condensation conditions are identical, i.e. that... 

Similar results with graphitized carbon blacks have been obtained for the heat of adsorption of argon,krypton,and a number of hydrocarbons (Fig. 2.12). In all these cases the heat of adsorption falls to a level only slightly above the molar heat of condensation, in the vicinity of the point where n = n . 

When water vapor condenses to liquid water, the molecules release the energy it took to separate them. A mole of gaseous water, therefore, will release 10 kilocalories of heat when condensed to liquid water at the same temperature. The amount of heat released is numerically equal to the molar heat of vaporization. 

The equation shows the change in enthalpy when one mole of liquid water vaporizes into water vapor. This is called the molar heat of vaporization. Given this information, which of these is the proper value for the molar heat of condensation ... 

The number of molecules passing in each direction from vapour to liquid and in reverse is approximately the same since the heat given out by one mole of the vapour on condensing is approximately equal to the heat required to vaporise one mole of the liquid. The problem is thus one of equimolecular counterdiffusion, described in Volume 1, Chapter 10. If the molar heats of vaporisation are approximately constant, the flows of liquid and vapour in each part of the column will not vary from tray to tray. This is the concept of constant molar overflow which is discussed under the heat balance heading in Section 11.4.2. Conditions of varying molar overflow, arising from unequal molar latent heats of the components, are discussed in Section 11.5. 

Trouton s rule phys chem An approximation rule for the derivation of molar heats of vaporization of normal liquids at their boiling points. traCit anz. riil ) true condensing point See critical condensation temperature. trii kan dens ir). point) true electrolyte puys chem A substance in the solid state that consists entirely of ions. trir i lek-tr9,lTt)... 

However, AH, the difference between the molar enthalpy of the gas and the condensed phase, depends in general on both the temperature and the pressure. The enthalpy for an ideal gas is independent of pressure and, fortunately, the enthalpy for the condensed phase is only a slowly varying function of the pressure. It is therefore possible to assume that AH is independent of the pressure and a function of the temperature alone, provided that the limits of integration do not cover too large an interval. With this final assumption, the integration can be carried out. When the molar heat capacities of the two phases are known as functions of the temperature, AR is obtained by integration. If ACP, the difference in the molar heat capacities of the two phases, is expressed as... 

The coefficient of thermal expansion a of a condensed substance is related to the molar heat capacities cp at constant pressure. The above equation (dv/dT)p = (ds/dp)T for one mole can be differentiated with respect to T and combined with (ds/dT)p = cp/T to obtain the following equation ... 

In order to maintain the simplest model that accounts for multisite-occupancy in multilayers we define it in the spirit of the BETs original formulation. The adsorbent is a homogeneous lattice of sites. The adsorbate is assumed as linear molecules having k identical units (k-mers) each of which occupies an adsorption site. Furthermore, i) a k-mer can adsorb on empty sites in the first layer or exactly onto an already adsorbed one ii) no lateral interactions are considered iii) the adsorption heat in all layers, except the first one, equals the molar heat of condensation of the adsorbate in bulk liquid phase. Thus, c=qi/qi=qi/q with qi=q (1=2,...,oo) denotes the ratio between the single-molecule partition... 

Here qns and qno are heats of immersion of the zeolite initially containing ris and n<, moles of presorbed water per gram, and aHl is the molar heat of condensation of water, taken as 10.51 kcal per mole. The degree of presaturation, 6, is given by... 

Heat of condensation The amount of heat that must be removed from a specific amount of a vapor at its condensation point to condense the vapor with no change in temperature usually expressed in J/g or kj/mol in the latter case it is called the molar heat of condensation. 

The molar heats of vaporization of both components A and B are approximately equal. This means that 1 mol of condensing vapor releases enough heat to vaporize 1 mol of liquid. 

Apply The molar heat of vaporization of ammonia is 23.3 kl/mol. What is the molar heat of condensation of ammonia ... 

The molar heats of fusion and vaporization for silver are 11.3 kJ/mol and 250. kJ/mol, respectively. Silver s normal melting point is 962 °C, and its normal boiling point is 2212 °C. What quantity of heat is required to melt 12.5 g of silver at 962 °C What quantity of heat is liberated when 4.59 g of silver vapor condenses at 2212 °C ... 

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