Specific heat sodium hydroxide

Some solutes have large heats of solution, and care should be taken in preparing solutions of these substances. The heat evolved when sodium hydroxide dissolves is 44.5 kj/mol. What is foe final temperature of foe water, originally at 20.0°C, used to prepare 1.25 L of 6.00 M NaOH solution Assume that all the heat is absorbed by 1.25 L of water, specific heat = 4.18 J/g °C. 

Some agrochemicals bind strongly to the soil component as bound residues, which cannot be extracted without vigorous extraction procedures. In this case, an acidic (e.g., hydrochloric acid, sulfuric acid) or alkaline solution (e.g., sodium hydroxide, potassium hydroxide) can be used as an extraction solvent, and also heating may be effective in improving the extraction of the residues. Analytical procedures after the extraction are the same as above, but a filtration procedure may be troublesome in some of these situations. However, these procedures are rare exceptions or are needed for specific chemicals that are stable under such harsh extraction conditions. 

Another classic resolution process developed by Ethyl Corp. for (S)-ibuprofen production uses (S)-(-)-a-methylbenzylamine (MAB) as the chiral base for diastereomeric salt formation 49 The difference in solubility between (S)- and (ft)-ibuprofen MAB salts is so substantial that only half an equivalent of MAB is used for each mole of racemic ibuprofen, and no seeding is needed. The process can also be performed in a wide range of solvents, and the unwanted (ft)-ibuprofen can be recycled conveniently by heating the mother liquor in sodium hydroxide or hydrochloric acid. Other designer amines have been developed for resolution of ibuprofen with good stereoselectivities,50 but these chiral amines were prepared specifically for ibuprofen resolution and are thus unlikely to be economical for industrial production. 

Optical (Specific) Rotation Transfer an accurately weighed amount of sample, equivalent to about 100 mg of total tocoph-erols, into a separator, and dissolve it in 50 mL of ether. Add 20 mL of a 10% solution of potassium ferricyanide in a 1 125 sodium hydroxide solution, and shake for 3 min. Wash the ether solution with four 50-mL portions of water, discard the washings, and dry over anhydrous sodium sulfate. Evaporate the dried ether solution on a water bath under reduced pressure or in an atmosphere of nitrogen until about 7 or 8 mL remains, and then complete the evaporation, removing the last traces of ether without the application of heat. Immediately dissolve the residue in 5.0 mL of isooctane, and determine the optical rotation. Calculate the optical rotation [see Optical (Specific) Rotation, Appendix HB], using as c the concentration expressed as the number of grams of total tocopherols, as determined in the Assay (above), in 100 mL of the solution. 

Resin Preparation. All phenolic resins were prepared in the laboratory. Resin preparations were replicated one time. To prepare each resin, all phenol and water were placed in a reaction kettle. The formaldehyde was added in three steps 1) total formaldehyde less 1 mole of formaldehyde was added at the beginning 2) the balance was divided into two equal parts (i.e., 0.5 mole each), one of which was added 1 hour after the reaction began and 3) the remainder of formaldehyde was added 20 minutes later. The sodium hydroxide was added as catalyst in four steps (i.e., four equal parts at 10-minute intervals). To initiate the reaction, the mixture was heated and maintained at 75 °C. All reactions were terminated at the end of 100 minutes. Gel time, pH, viscosity, solid content, and specific gravity were determined. The general conditions for resin preparation were ... 

In order for starch molecules to become detached from one another, they must be hydrated, a process accomplished in water slurry by using either thermal or chemical energy. Only then will the molecules be separated and uncoiled enough to be able to latch onto other separate particles and act as an adhesive. The most common form of chemical hydration of starch is through the use of aqueous alkali. Sodium hydroxide is capable of hydrating starch molecules without heat, but a specific minimum concentration must be reached for that to occur (2). 

An ideal mixture is one for which the heat of mixing or solution is negligible and so Hmixture 21 where n, is the amount of mixture component i and D, is the specific enthalpy of the pure component at the temperature and pressure of the mixture. Up to now in this text, we have assumed ideal mixture behavior for all mixtures and solutions. This assumption works well for nearly all gas mixtures and for liquid mixtures of similar compounds (such as mixtures of paraffins or of aromatics), but for other mixtures and solutions—such as aqueous solutions of strong acids or bases or certain gases (such as hydrogen chloride) or solids (such as sodium hydroxide)—heats of solution should be included in energy balance calculations. This section outlines the required procedures. 

Fourdrinier machine—The machine that forms paper from pulp, named after the English family that financed its development in the early 1 800s. Furnish—Specific combination of pulp and other ingredients used to make a particular kind of paper. Kraft process—process in which sodium sulfate is reduced by heating with carbonaceous matter in a furnace to form sodium sulfide, which is then used in a water solution with sodium hydroxide as a cooking liquor. The wood pulp is then cooked under pressure and at high temperatures. The kraft process, also known as the sulfate process, has a less corrosive influence on iron and steel than the sulfite process. 

A specific description of a preferred practice of the invention with vanillin as the aromatic compound is as follows. Vanillin is dissolved in water with one molar equivalent of sodium hydroxide while the solution is warmed to 50°-100° C. One molar equivalent of iodine and two molar equivalents of sodium iodide are added to water to prepare one molar equivalent of NalS.Nal. This sodium triiodide solution is added to the sodium vanillate solution along with a catalytic amount of sulfuric acid--preferably from 5 to 10 mole %. The mixture is stirred about one hour at a temperature of 50°-100° C., then sodium hydroxide is added to make the solution alkaline (from 1 to 5N). The copper catalyst is then added and the mixture heated at reflux until the iodovanillin is consumed, about 12 hours. The excess hydroxide is then neutralized and the 5-hydroxyvanillin extracted with a water-immiscihle organic solvent. The aqueous phase bearing the sodium iodide is then subjected to oxidizing conditions and the resultant iodine precipitates from solution. The solid element is filtered out, and a sodium triiodide solution prepared by reducing a portion of the iodine to sodium iodide and dissolving the iodine in the iodide to make the sodium triiodide solution. 

A 50.0-mL sample of 0.400 M copper(II) sulfate solution at 23.35°C is mixed with 50.0 mL of 0.600 M sodium hydroxide solution, also at 23.35°C, in the coffee-cup calorimeter of Example 15-1. After the reaction occurs, the temperature of the resulting mixture is measured to be 25.23°C. The density of the final solution is 1.02 g/mL. Calculate the amount of heat evolved. Assume that the specific heat of the solution is the same as that of pure water, 4.184 J/g-°C. 

In certain cases side chains of aromatic compounds can be oxidized in an oxidizing alkali melt — the substance is heated at 200-300° with 3-4 parts of solid sodium hydroxide or potassium hydroxide to which a little water is added. This process has been recommended specifically for homologous phenols since the experiment can be made with the free phenol. An example is the conversion of 2,4-xylenol into 2-hydroxy-5-methylbenzoic acid, which shows also that the alkyl group next to the hydroxyl group is preferentially oxidized.400... 

Primary aromatic amines can be converted into the corresponding hydroxy compounds in various ways. In some cases this can be done by use of dilute acid or alkali under specific conditions, but that method is used mainly in industry and is rarely suitable for laboratory practice. 4-Amino-2,7- and -2,6-naphthalenedisulfonic acid and 8-amino-1,6-naphthalenedisulfonic acid are converted quantitatively into the corresponding hydroxynaphthalenedisulfonic acids when their acid salts are heated in water at 180° 555 and 2-methoxy-4-nitroaniline affords 4-nitroguaiacol in 86% yield when boiled for 30 hours with aqueous sodium hydroxide.556... 

A specific identification test for urea is the enzymatic reaction with urease. 50 mg of powdered resin or 0.1 ml of the resin solution is carefully heated in a test tube with a Bunsen burner until all formaldehyde has been removed (check odor ). After cooling and neutralizing with 10% sodium hydroxide using phenolphthalein as an indicator, 1 drop of 1 N sulfuric acid and 0.2 ml of a freshly prepared 10% urease solution are added. A moist piece of litmus paper is then attached to the upper rim of the test tube. After a short time, the blue coloration of the indicator paper demonstrates the presence of ammonia which is formed only by urea-containing resins and not by melamine resins. Hexamethylene tetramine is the only substance that may interfere with this reaction. 

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