Water and sodium metal

Example Between sodium metal and water 2Na(s) + 2H20(i) 2NaOH(aq) + H2(g)... 

If we write a similar expression to that in Equation (7.40) for the reaction between sodium metal and water in Equation (7.35), then we would have to write the term for the hydrogen couple first rather than second, because the direction of change within the couple is reversed. In fact, any couple that caused hydrogen gas to form protons would be written with the hydrogen couple first, and any couple that formed hydrogen gas from protons (the reverse reaction) would be written with the hydrogen term second. 

The reaction between sodium metal and water is shown in the Sodium and Potassium in Water movie eChapter 14.14). Write and balance the equation for this reaction. Is this an oxidation-reduction reaction If so, identify the oxidizing and reducing agents. 

Focusing on the functional groups in a molecule allows us to recognize patterns in the behavior of related compounds. Consider what we know about the reaction between sodium metal and water, as an example. 

What is the relationship between AH and AE for a process To find out, let us consider the reaction between sodium metal and water ... 

To illustrate the concepts we have introduced, considCT the reaction at 25°C of sodium metal and water, carried out in a beaker opai to the atmosphere at 1.00 atm pressure. 

Sodium hydroxide reacting with hydrogen gas to produce sodium metal and water... 

The reaction between sodium metal and water produces sodium and hydroxide ions and hydrogen gas. Calculate AG° for the formation of one mole of hydrogen gas at 25°C and 50°C (2 significant figures). 

Into a 3-1., three-necked flask (Note 1) equipped with a reflux condenser and an efficient stirrer is placed 11. of absolute (99.8%) ethanol. To this is added 39.4 g. (1.72 g. atom) of sodium metal, and, after solution is complete (Note 2), 91.5 ml. (97.2 g., 0.86 mole) of ethyl cyano-acetate (Note 3) and 51.5 g. (0.86 mole) of urea are added. The mixture is heated under reflux on a steam bath with vigorous stirring for 1 hours. After about 2 hours, the reaction mixture becomes practically solid, and the stirrer may have to be stopped. At the end of the reac-I ion time, 1 1. of hot (80°) water is added to the reaction mixture, and si i rring is resumed. After complete solution has taken place, the stirred mixture is heated at 80° for 15 minutes and is then neutralized to litmus with glacial acetic acid (Note 4). Additional glacial acetic acid (75 ml.) is then added, followed by cautious addition of a solution of 64.8 g. (0.94 mole) of sodium nitrite dissolved in 70 ml. of water. The rose-red nitroso compound separates almost immediately as an expanded precipitate which almost stops the stirrer. After a few minutes the ni-... 

Electrolysis is used to decompose many compounds into their constituent elements. You have seen this process with water. Another example is the electrolysis of molten sodium chloride to yield molten sodium metal and chlorine gas ... 

Alcohols, (a) Monohydric The common impurities in alcohols are aldehydes or ketones, and water. [Ethanol in Chapter 3 is typical.] Aldehydes and ketones can be removed by adding a small amount of sodium metal and refluxing for 2 hours, followed by distillation. Water can be removed in a similar way but it is preferable to use magnesium metal instead of sodium because it forms a more insoluble hydroxide, thereby shifting the equilibrium more completely from metal alkoxide to metal hydroxide. The magnesium should be activated with iodine (or a small amount of methyl iodide), and the water content should be low, otherwise the magnesium will be deactivated. 

M. D. Alexander, "Reactions of the Alkali Metals with Water A Novel Demonstration/ J. Chem. Educ., Vol. 69,1992,418. The reaction of sodium metal with water to produce an aqueous solution of sodium hydroxide and hydrogen gas is performed at the interface between paint thinner and the more dense water. Periodically, bubbles of hydrogen gas carry the sodium metal into the organic layer, temporarily stopping the reaction. The presence of the aqueous layer is shown by a phenol-phthalein indicator color change. 

Figure 4.2 Water falls onto pure sodium metal and creates a fiery chemical reaction. Pure alkali metals such as sodium are quite volatile. Because of this, alkali metals are generally stored in oil or wax.

As mentioned earlier, direct thermal dissociation of water requires temperatures above approximately 2500 K. Since there are not yet technical solutions to the materials problems, the possibility of splitting water instead, by various reaction sequences, has been probed. Historically, the reaction of reactive metals and reactive metal hydrides with water or acid was the standard way of producing pure hydrogen in small quantities. These reactions involved sodium metal with water to form hydrogen or zinc metal with hydrochloric acid or calcium hydride with water. All these... 

If a phosphate was present, the precipitate obtained on addition of ammonium chloride and hydroxide may contain phosphates of such metals as calcium, etc., which are normally precipitated in later groups in systematic analysis. The precipitate is therefore dissolved in dilute hydrochloric acid, and the solution nearly neutralised with sodium carbonate. Sodium acetate is now added, and the whole boiled. The precipitate contains the phosphates of aluminium, chromium, and iron, and is treated, as already indicated, with sodium peroxide and water. 

Practice Problem 10.7 The industrial process for the production of sodium metal and chlorine gas involves electrolysis of molten (melted) sodium chloride (in the absence of water). Calculate the mass of sodium that can be prepared by electrolysis of 207 kg of sodium chloride. The balanced equation is... 

Compounds of Sodium. The most important compound of sodium is sodium chloride common salt), NaCl. It crystallizes as colorless cubes, with melting point 801° C, and it has a characteristic salty taste. It occurs in sea water to the extent of 3%, and in solid deposits and concentrated brines (salt solutions) that are pumped from wells. Many million tons of the substance are obtained from these sources every year. It is used mainly for the preparation of other compounds of sodium and of chlorine, as well as of sodium metal and chlorine gas. 

Even when you get a pure substance, like distilled water, it isn t necessarily a simple substance made up of one element. If you pass electricity through water, for example, the water splits up into hydrogen gas and oxygen gas. If you melt pure salt (800 °C or 1073 K) and pass electricity through it, it splits up into sodium metal and chlorine gas. 

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