Specific heats, aqueous solutions

The specific heat of aqueous solutions of hydrogen chloride decreases with acid concentration (Fig. 4). The electrical conductivity of aqueous hydrogen chloride increases with temperature. Equivalent conductivity of these solutions ate summarized in Table 8. Other physicochemical data related to... 

Fig. 4. Specific heat of aqueous solutions of hydrogen chloride.

Monobasic aluminum acetate is dispensed as a 7% aqueous solution for the topical treatment of certain dermatological conditions, where a combination of detergent, antiseptic, astringent, and heat-dispersant effects are needed (12). The solution, diluted with 20—40 parts water, is appHed topically to the skin and mucous membranes as a wet dressing (13). Burrow s solution, prepared from aluminum subacetate solution by the addition of a specific amount of acetic acid, is also used as a topical wet dressing. Standards of purity and concentration have been estabHshed for both pharmaceutical aluminum acetate solutions (13). Each 100 mL of aluminum subacetate solution yields 2.30—2.60 g of aluminum oxide and 5.43—6.13 g of acetic acid upon hydrolysis. For the Burow s solution, each 100 mL yields 1.20—1.45 g of aluminum oxide and 4.25—5.12 g of acetic acid. Both solutions may be stabilized to hydrolysis by the addition of boric acid in amounts not to exceed 0.9% and 0.6% for the subacetate and Burow s solutions, respectively (13). 

Table 7. Specific Heats of Aqueous Solutions of Ammonium Nitrate at 100°C...

To convert from kPa to mm Hg, multiply by 7.5. Values for the specific heat of aqueous borax (73) solutions as a function of weight percent decahydrate are... 

Now it has been shown that the difference of the specific heats of the solution and solvent is proportional to the concentration, in the case of aqueous solutions ( 10). Assuming, therefore, in general... 

Figure 5.1 is a graph of the specific heat capacity cp (heat capacity per gram) of aqueous sulfuric acid solutions at T — 298.15 K against A, the ratio of moles of water to moles of sulfuric acid. The values plotted were obtained from a very... 

For dilute aqueous solutions it is usually sufficient to take the specific heat of the solution as that of water. 

A deliquescent material takes up moisture freely in an atmosphere with a relative humidity above a specific, well-defined critical point. That point for a given substance is defined as the critical relative humidity (RH0). Relative humidity (RH) is defined as the ratio of water vapor pressure in the atmosphere divided by water vapor pressure over pure water times 100% [RH = (PJP0) X 100%]. Once moisture is taken up by the material, a concentrated aqueous solution of the deliquescent solute is formed. The mathematical models used to describe the rate of moisture uptake involve both heat and mass transport. 

The mass, m, is the mass of the solution, because the solution absorbs the heat. When a dilute aqueous solution is used in a calorimeter, you can assume that the solution has the same density and specific heat capacity as pure water. As you saw above, you can also assume that the heat capacity of the calorimeter is negligible. In other words, you can assume that all the heat that is released or absorbed by the reaction is absorbed or released by the solution. 

The specific heats of aqueous solutions of glycolamide at 25°C ate listed in... 

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