Calcium, reaction with water experiment

Experiment 8.—To 5 c.c. of freshly distilled acetaldehyde in a moderate-sized conical flask one drop of concentrated sulphuric acid is added with cooling. When the vigorous reaction is over, the paraldehyde produced is shaken in a small separating funnel with water in order to remove the sulphuric acid, and the polymeride, which is insoluble in water, is separated if necessary by extraction with ether. After being dried with a little calcium chloride the substance is distilled from a small distilling flask. Boiling point 124°. 

Properties of Calcium Carbide. (Perform the experiment in a fume cupboard ) Assemble an apparatus (see Fig. 76) and check its tightness. Put one or two small pieces of calcium carbide into the dry Wurtz flask and pour water into the dropping funnel. By adding the water dropwise to the calcium carbide, pass a stream of the gas formed through the apparatus (for what purpose ), then collect the gas in a test tube over water and test it with a burning splinter. What happens Write the equation of the reaction. 

Tip The calcium hydroxide can be suspended in the Erlenmeyer flask with a little water gaseous carbon dioxide is added, and it is then closed off with a stopper and glass tube. If the flask is connected to a syringe which is filled with carbon dioxide, it is then possible to see the reaction of calcium hydroxide with the gas the piston is sucked into the syringe. This experiment can simulate the setting and reaction of calcium mortar in the air. 

The geochemical balance of a 103 acre watershed underlain by silicate bedrock was investigated. Base flow composition of the stream water was essentially constanty but flood flows showed a decrease in concentration of silica, bicarbonate, and sodium and an increase in sulfate, magnesium, calcium, and potassium. Laboratory experiments indicate that fresh rock or soil reacts rapidly with distilled water and achieves a composition similar to the stream water, suggesting control of water composition by reaction with the silicate minerals. The aluminosilicate minerals react with CO charged water to form kaolinite, releasing cations and silica to solution. The products of weathering are removed as particulate matter (0,28 metric tons per year) and dissolved material (1,5 metric tons per year). 

Many organic reagents react rapidly and preferentially with water. The success or failure of many experiments depends to a large degree on how well atmospheric moisture is excluded from the reaction system. The "drying tube," which is packed with a desiccant such as anhydrous calcium chloride, is a handy way to carry out a reaction in an apparatus that is not totally closed to the atmosphere, but... 

It is emphasized that the data in Table III do indicate a trend of increased lattice distortion and possibly calcium solution with increased water contamination. It is noted that all the samples investigated by Taylor were reacted for only 60 min, which is near or slightly past the end of the initial portion of the reaction in most samples. In contrast, Verduch in earlier work reacted the samples for 24 hr before conducting X-ray analyses. As a result, a quantitative comparison of the two studies cannot be made. The low values of calcium solid solution reported by Verduch as compared to Taylor s study may actually be due to the longer reaction times. Taylor s experiments performed at the peak of the initial reaction may have caught the calcium solid solution at its maximum. This conclusion is supported by the fact that the lattice parameters decreased in reheating experiments (sample E). 

You see that vacuum adapter stuck to the top of the condenser in fig. 7a Well, a closer look at it in fig. 7b will show that it has some drying agent sandwiched between two cotton balls and the nipple (tee heel) sealed with plastic wrap or foil. The drying agent can be either a commercial product called Drierite or calcium chloride. This attachment is placed on top of a condenser when refluxing solutions that have no water in them and must remain that way during the time they are refluxed. All this is to prevent moisture in the outside air from coming into contact with the cold surface of the of the inside walls of the condenser. This will surely happen and the condensed outside-air water will drip down into the reaction flask and ruin the experiment. This is not so much a... 

Experiments illustrating these various possible reactions have been carried out notably by Reinders (Z it. Roll. Ghem. xiii, 235, 1913) and by Hofmann (Zeit. Phys. Ghem. Lxxxiii. 385,. 1913). Finely divided calcium sulphate is preferentially wetted by water in the presence of liquids, such as chloroform and benzene which are frequently termed non-polar or slightly polar. Silver iodide suspensions in water will go into the dineric interface in contact with ether, chloroform and benzene, but are removed from the water by preferential wetting in the case of butyl and amyl alcohols, whilst the reverse holds true in the case of aqueous suspensions of arsenious sulphide. 

Preparation. Perform the experiment in a fume cupboardl) Add 10-15 ml of water to 2 g of pure slaked lime (calcium hydroxide) and stir thoroughly. Put the mixture in a small beaker cooled with ice (why is cooling needed ) and pass chlorine purified from hydrogen chloride (how can this be done ) through it during 10-20 min. Write the equation of the reaction. 

Mix 0.5 gram of the precipitated silica with 1 gram of powdered calcium fluoride. Place the mixture in a test tube, moisten it with 36 N H2S04, and warm it gently under the hood. Dip a stirring rod in water and lower it, with a drop adhering, into the gas in the test tube. Note the precipitate that forms in the drop of water. Write equations for all the reactions, and state what rather unusual properties are shown by this experiment to be possessed by hydrofluoric acid and by silicon tetrafluoride. 

---