Potassium hydroxide calculating normality

In a 500-cc. three-neck flask, fitted with a reflux condenser and a mechanical stirrer (Note t), is placed 45.5 g. (0.25 mole) of 2,4-dinitrotoIuene (Note 2), 85 g. (1.5 moles) of iron (Note 3), and 100 cc. of 50 per cent (by weight) ethyl alcohol (Note 4). The mixture is heated to boiling on a water bath, the stirrer is started (Note 5) and a solution of 5.2 cc. (0.06 mole) of concentrated hydrochloric acid in 25 cc. of 50 per cent (by weight) ethyl alcohol is added slowly (Note 6). The mixture is refluxed for two hours after addition of the acid is complete. At the end of this time the apparatus is disconnected and the hot mixture is made just alkaline to litmus by the addition of the calculated amount of 15 per cent alcoholic potassium hydroxide solution (Note 7). Without allowing the mixture to cool, the iron is removed by filtration and the reaction flask is rinsed with two 50-cc. portions of 95 per cent ethyl alcohol the same alcohol is used to wash the iron residue. To the filtrate is added 84 cc. of 6 N sulfuric acid the normal sulfate of 2,4-diaminotoluene precipitates. The mixture is cooled to 250 and filtered by suction. The product is washed with two 35-rc. portions of 95 per... 

The saponification value is the amount of alkali required to saponify a defined amount of sample. It is expressed in mg potassium hydroxide (KOH) per g sample. The procedure involves the use of excess alcoholic KOH, which catalyzes the saponification/release of the free fatty acids from the glycerol backbone. The unreacted KOH is then back-titrated with standardized hydrochloric acid (HC1) using phenolphthalein as the indicator. The amount and normality of the HC1 used for neutralization can then be used to calculate the saponification value. The saponification value provides evidence as to the relative chain lengths of the fatty acids in the system. 

Potassium Hydroxide, 0.5 N, Alcoholic (Caution The solution may become very hot. Allow it to cool before adding the aldehyde-free alcohol.) Dissolve about 35 g of potassium hydroxide (KOH) in 20 mL of water, and add sufficient aldehyde-free alcohol to make 1000 mL. Allow the solution to stand in a tightly stoppered bottle for 24 h. Then quickly decant the clear supernatant liquid into a suitable, tight container, and standardize as follows Transfer quantitatively 25 mL of 0.5 N hydrochloric acid into a flask, dilute with 50 mL of water, add 2 drops of Phenolphthalein TS, and titrate with the alcoholic potassium hydroxide solution until a permanent, pale pink color is produced. Calculate the normality. Store this solution in tightly stoppered bottles protected from light. 

Crude oils may be up to 15% FFA, while refined oils will be <0.1%. Measurement of FFA is normally done by titration of an ether-ethanol solution of the fat with standardized aqueous sodium or potassium hydroxide, in the presence of phenolphthalein indicator (see ISO 660 1983). This method is very accurate, using the molecular weight of oleic acid (282) for all calculations. Accuracy is improved by using the average molecular mass of the fatty acids in the fat, calculated from the FA composition (e.g., for palm oil 256 is used, for palm kernel/coconut oil 200 is used). The results are expressed either as acid value the number of milligrams of potassium hydroxide required to neutralize 1 g of the fat, or, FFA% the percentage concentration of oleic acid equivalent to the free acids present. 

Dissolve 5 g of K103 and 5 g of potassium hydroxide in 50 cm of water. Boil, then dissolve in the solution 8 g of potassium persulphate. After 5 minutes add 3 g of potassium hydroxide, pellet by pellet. Heat the solution on a boiling water-bath for 30 minutes and add 50 cm of hot water, stir until all the precipitated potassium sulphate has dissolved, then cool. Filter off any insoluble material through GF paper, place the beaker containing the solution in a bath of cold water, and while stirring well, run in a 1 1 concentrated nitric acid water mixture from a burette until the solution is acid to methyl orange then add 1 cm of the acid in excess. Wash the precipitated product with cold water, twice by decantation, and then on a filter. Air dry at normal temperature and weigh your product and calculate the % yield based on I. 

Procedure. Two 10 00 portions of a 10 per cent solution of hydrosylamine hydro-cMoride are added by pipette to two 125 ce Erlenmeyer flasks. To one of these flasks is then added a thimble beaker containing an accurately weighed sample of the solution to be analyzed. This sample should contaha approximately 1 g formaldehyde. If resinous material is present and precipitates,-a small quantity of methanol, fi.f, 10 cc, may be added to dissolve the precipitate. A similar amount of methanol should also be added to the solution in the other flask, which serves as a blank or control. After approximately 15 to 20 minutes, the contents of both flasks should be titrated with normal potassium hydroxide, using bromophenol blue as an indicator. The end-point is marked by a color change from yellow to light purple, fllhe blank should require only a few ce of standard alkali and should be checked daily. The per cent formaldehyde la calculated by the following formula ... 

Sodium Hydroxide, 1N (40.00 g NaOH per 1000 mL) Dissolve about 40 g of sodium hydroxide (NaOH) in about 1000 mL of carbon dioxide-free water. Shake the mixture thoroughly, and allow it to stand overnight in a stoppered bottle. Standardize the clear liquid as follows Transfer about 5 g of primary standard potassium biphthalate [ KHCgH4(COO )2], previously dried at 105° for 2 h and accurately weighed, to a flask, and dissolve it in 75 mL of carbon dioxide-free water. If the potassium biphthalate is in the form of large crystals, cmsh it before drying. To the flask add 2 drops of Phenolphthalein TS, and titrate with the sodium hydroxide solution to a permanent pink color. Calculate the normality. Each 204.2 mg of potassium biphthalate is equivalent to 1 mL of 1 N Sodium Hydroxide. 

---