Is the glass half empty or half full? Is the glass half empty or half full? "Is the glass half empty or half full?" is a common expression, a proverbial phrase, generally used rhetorically to indicate that a particular situation could be a cause for optimism (half full) or pessimism (half empty), or as a general litmus test to simply determine an individual's worldview. The purpose of the question is to demonstrate that the situation may be seen in different ways depending on one's point of view and that there may be opportunity in the situation as well as trouble. Another perspective comes from psychology, where research has
Fehling's solution the starch sugar. Formic acid (HCOH) also gives a positive Fehling's test result, as it does with Tollens' test and Benedict's test also. The positive tests are consistent with it being readily oxidizable to carbon dioxide. The net reaction between an aldehyde and the copper(II) ions in Fehling's solution may be written as: or with the tartrate included: Sodium hydroxide is corrosive. Fehling's solution Fehling's solution is a chemical reagent used to differentiate between water-soluble carbohydrate and ketone functional groups, and as a test for reducing sugars and non-reducing sugars, supplementary to the Tollens' reagent test. The test was developed