Determination of Hydration Numbers by Near Infrared Modification of an Earlier Approach Jerrold Jayne San Francisco State University, San Francisco. CA 94132 Recently J. Leland Hollenherg ( I ) described a method for determining hydration numbers for solutes in aqueous solutions based on measurements of absor~tionin the near infrared. Absorption a t 958 nm appears tb be due primarily to non-hvdroeen-bonded water. If a ~ ~ r o ~ r assum~tions iate are - made one can determine the fractio; of the wate; that has been removed from water into a solute's hvdration s ~ h e r hv e measuring the decrease in absorption at 958 nm. his, in tun;, leads to values for the spectroscopic hydration number of the solute. The method was devised by Bonner and Woolsey (2). Hollenherg's contribution was to clarify it and prepare it as a laboratory experiment. Careful examination of Bonner and Woolsey's assumptions shows that they are self-contradictory. An alternative set of assumptions can he made that leads to a self-consistent interpretation of the experimental data. The principal purpose of this paper is to use this example of literature error to illustrate several principles that are often difficult to present to chemistry students persuasively. A second purpose is t o indicate how the significance of Bonner and Woolsey's resulta is changed when their assumptions are replaced by a selfconsistent set. Bonner and Woolsey assume that there me three types of water in a solution: water of hydration, represented as H, hydrogen-bonded hulk water, X, and monomeric non-hydroeen-bonded bulk water. re~resented as ''H.0'' hv ~ o h n h e r gbut , here representedas ..M". Wc will inboduce the s ~ m h o l sW,f'or the total molar concentration ofall tvoes of water in a sofution and W , for the total molar concentra
