Nomograph for Sodium Hydroxide Solutions
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R. C. KINTNER Illinois institute of Technology, Chicago, 111.
THE
enthalpy concentration chart for sodium hydroxide solutions (7) is now a standard item in texts dealing with evaporation. Tracing one of the curving isotherm3 to its intersection with a concentration line and reading the corresponding enthalpy is a somewhat uncertain matter, particularly a t the highest values. I t was observed that, a t a specific concentration, the specific heat is very nearly constant over the entire temperature range. Therefore, H = Cp(t - t o ) , in which t o is the reference temperature, usually 32' F. One need merely construct two convenient parallel and uniform scales of the proper range and then cross-plot the available data for several concentrations to locate the nonuniform, curved scale. This chart has been used for teaching purposes for several years and found much easier to use than the usual form. A copy (Vi,X 11 inches) may be obtained by wriring : Chemical Engineering Department, Illinois Institute of Technology, Chicago 16, Ill.
literature Cited (1) McCabe, IV. L., Trans. Am. Inst. Chem. Engrs. 31, 129 (1935).
RECEIVED for review January 13, 1959 ACCEPTED February 3, 1959
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INDUSTRIAL AND ENGINEERING CHEMISTRY
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ENTHALPY- CONCENTRAT ION CHART SODIUM HYDROXIDE SOLUTIONS (BASIS132" F.)
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