Calcium and water

Assuming calcium metal reacts in a similar way, write the equation for the analogous reaction between calcium and water. Remember that calcium is in the second column of the periodic table and sodium is in the first. 

Calcium and Water. Drop a few pieces of metallic calcium (in the form of turnings) into a test tube of clear... 

An important factor that affects the rate of a chemical reaction is the reactive nature of the reactants. As you know, some substances react more readily than others. For example, calcium and sodium are both reactive metals however, what happens when each metal is added to water is distinctly different. When a small piece of calcium is placed in cold water, as shown in Figure 17-7a, the calcium and water react slowly to form hydrogen gas and aqueous calcium hydroxide. 

Henry Cavendish was one of the great English amateur scientists. He came from a wealthy family from the line of the Dukes of Devonshire, although he was not personally wealthy until later in his life. He went to Cambridge to study but never graduated. Cavendish was a very private person and conducted most of his work for his own interest, publishing only three major papers, one on his discovery of inflammable air (what we call hydrogen), one on the relation of fixed air, calcareous matter (calcium), and water, and one a study of the composition of the atmosphere. 

Other functions of oligosaccharides which have been tabulated are the sink and depot function (12 examples). Thus calcium and water are bound and... 

Calcium and the elements below it react readily with water at room temperature (although more slowly than the alkali metals adjacent to them in the periodic table). The reaction between calcium and water ( FIGURE 7.24), for example, is... 

Write the balanced chemical equation for the reaction between calcium and water 19,.61 17.52 -0.37 -0.86... 

Recall from Section 4.9 that oxidation is the loss of electrons, and reduction is the gain of electrons. Recall also that we can identily oxidation-reduction reactions through changes in oxidation states oxidation corresponds to an increase in oxidation state and reduction corresponds to a decrease in oxidation state. For example, consider the following reaction between calcium and water ... 

Lime with tallow-derived fatty acids they are the so-called calcium greases that are often used as subframe greases and water-resistant greases. 

Group II hydrogencarbonates have insufficient thermal stability for them to be isolated as solids. However, in areas where natural deposits of calcium and magnesium carbonates are found a reaction between the carbonate, water and carbon dioxide occurs ... 

Such water, and also that containing salts of multipositive metals, (usually sulphates), is said to be hard since it does not readily produce a lather with soap. Experiments with alkali metal salts can be performed to verify that the hardness is due to the presence of the multipositive metal ions and not to any of the anions present. The hardness due to calcium and magnesium hydrogencarbonates is said to be temporary since it can be removed by boiling ... 

It is thus important to determine the relative amounts of calcium and magnesium, for addition of too much lime means that calcium ions are reintroduced into the water, i.e. it becomes hard again, the hardness being permanent. 

Reflux a mixture of 68 g. of anhydrous zinc chloride (e.g., sticks), 40 ml. (47 -5 g.) of concentrated hydrochloric acid and 18-5 g. (23 ml.) of sec.-butyl alcohol (b.p. 99-100°) in the apparatus of Fig. 777, 25, 1 for 2 hours. Distil oflF the crude chloride untU the temperature rises to 100°. Separate the upper layer of the distillate, wash it successively with water, 5 per cent, sodium hydroxide solution and water dry with anhydrous calcium chloride. Distil through a short column or from a Claisen flask with fractionating side arm, and collect the fraction of b.p. 67-70° some high boiling point material remains in the flask. Redistil and collect the pure cc. butyl chloride at 67-69°. The yield is 15 g. 

Mix 40 g. (51 ml.) of isopropyl alcohol with 460 g. (310 ml.) of constant boiling point hydrobromic acid in a 500 ml. distilling flask, attach a double surface (or long Liebig) condenser and distil slowly (1-2 drops per second) until about half of the liquid has passed over. Separate the lower alkyl bromide layer (70 g.), and redistil the aqueous layer when a further 7 g. of the crude bromide will be obtained (1). Shake the crude bromide in a separatory funnel successively with an equal volume of concentrated hydrochloric acid (2), water, 5 per cent, sodium bicarbonate solution, and water, and dry with anhydrous calcium chloride. Distil from a 100 ml. flask the isopropyl bromide passes over constantly at 59°. The yield is 66 g. 

The distillate contains alcohol, toluene and water, and may be dried with anhydrous potassium carbonate and used again for esterification after the addition of the necessary quantity of alcohol alternatively, the toluene may be recovered by washing with water, drying with anhydrous calcium chloride or anhydrous magnesium sulphate, and distiUing. 

The iso-nitrile may be removed by the following procedure. Shake the crude (undistilled) n-butyl cyanide twice with about half its volume of concentrated hydrochloric acid and separate carefully after each washing then wash successively with water, saturated sodium bicarbonate solution and water. Dry with anhydrous calcium chloride or anhydrous calcium sulphate, and distil. Collect the pure n-butyl cyanide at 139-141°. If a fraction of low boiling point is obtained (because of incomplete drying), dry it again with anhydrous calcium sulphate and redistil. The yield is 95 g. 

The following is a modification of the process described and gives quite satisfactory results. Wash the crude mixture of benzonitrile and dibromopentane with sodium carbonate solution until the latter remains alkaline, and then with water. Distil it under reduced pressure and collect the fraction boiling up to 120°/18 mm. Dissolve this in twice its volume of light petroleum, b.p. 40-60°, which has previously been shaken with small volumes of concentrated sulphuric acid until the acid remains colourless. Shake the solution with 6 per cent, of its volume of concentrated sulphuric acid, allow to settle, and run ofi the sulphuric acid layer repeat the extraction until the acid is colourless or almost colourless. Wash successively with water, sodium carbonate solution and water, dry over anhydrous calcium chloride or calcium sulphate, and distil off the solvent. Distil the residue under diminished pressure and collect the 1 6-dibromopentane at 98- 100°/13 mm. 

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