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EXPERIMENTS WITH GASES

 

With liquids we have worked, let gases. It is a little difficult, and above all, you need a tube with holes and vent tube.

The tube may be of glass, metal and even plastic. The rubber stopper is better not to take - it is difficult to drill holes. Take a cork or plastic stoppers - holes in them you can burn hot Shyla. In this hole, insert the tube, for example, from the eye dropper; it should enter into the hole of the tube tightly, with no gaps, so the hole in the tube should be done at first a little less than you want, and then gradually extend it to suit the diameter of the tube. Slip into a glass tube of rubber or plastic flexible tube length of 30 centimeters, at its other end also insert a short glass tube.

Now first experience with gases. Prepare lime water, the Gulf of hot water (1/2 Cup), half a teaspoon of powdered slaked lime, stir and allow to settle.

Transparent sediment settled on a solution and there is lime water. Carefully drain the liquid from the sediment; this laboratory technique is called decanting.

If you are not slaked lime CA(Oh)2, lime water can be prepared from two solutions sold in pharmacies: calcium chloride СаСl2 and ammonia NH4OH (aqueous ammonia solution). When mixed it also appears clear lime water.

Take a chilled bottle of mineral water or lemonade. Open the tube, quickly insert the neck of the tube with the exhaust tube and the other end will drop into a glass of lime water. Put the bottle in warm water. It will be released gas bubbles. This carbon dioxide CO2 (carbon dioxide, carbon dioxide). It is added to water to make it tastier.

The tube gas enters the glass, it passes through lime water, and she eyes becomes cloudy because it contains calcium hydroxide is converted to calcium carbonate, SASO3, and it is poorly soluble in water to form a white suspension.

To set up the experiment with lime water, the need to buy lemonade or mineral water. After all, when the breath we consume oxygen and released carbon dioxide, the same one that makes lime water to thicken. Lower the end of any clear tube in a fresh portion of lime water and exhale several times through the tube - the result will not keep itself waiting.

Open another bottle, insert the tube with the tube and continue to pass through lime water, carbon dioxide. Some time later, the solution will again become clear, because carbon dioxide reacts with calcium carbonate, turning it into another salt-bicarbonate CA(HCO3)2, and this salt is very soluble in water.

The following gas, which we will, was recently mentioned: ammonia. It is easily recognized by the characteristic sharp smell - the smell of pharmacy ammonia.

Pour into the bottle a little boiled saturated solution of washing soda. Then add ammonia, insert in the neck of the tube with a flexible outlet tube and at its other end put the test tube upside down. Pre-heat the bottle in warm water. A pair of ammonia is lighter than air, and soon they will fill the inverted test tube. Still holding the vial upside down, carefully lower it into a glass of water. Almost immediately, the water will begin to rise up in the tube, because ammonia is highly soluble in water, releasing a place for her in vitro.

At the same time you can learn to recognize the ammonia - and not only by smell. First, make sure that the ammonia solution has an alkaline reaction (use phenolphthalein or improvised indicators). Secondly, conduct a qualitative reaction for ammonia. Qualitative reaction is a reaction that can accurately identify a particular substance or group of substances.

Prepare a weak solution of copper sulphate (it should be pale blue) and lower in his exhaust pipe. When will be released ammonia NH3, the ends of the tube, the solution turns bright blue. The ammonia salt of copper gives brightly colored compound rather complex composition [Cu(NH3)4]SO4.

Now try to get a very small piece of calcium carbide - will receive acetylene. Assemble the device, as in the previous experiment, pour into the bottle, not ammonia, and soda. Lower it carefully wrapped in blotting paper is a small, pea-piece of calcium carbide and insert the tube with the tube. When blotting paper razmoknet, will be released gas, which you, as before, will be collected in an inverted test tube. A minute later, turn the test tube upside up and bring a lighted match. The gas will ignite and burn with a smoky flame. This is the acetylene, which is used by getosversion.

By the way, this experience is not only acetylene. The bottle is an aqueous solution of calcium hydroxide, i.e., lime water. It can be used for experiments with carbon dioxide.

Following the experience with the gases can be set only with good ventilation, and if it is not, in the fresh air. We will get that smell strongly of sulfur dioxide (sulfur dioxide) SO2.

Pour in a bottle of diluted acetic acid and add a little wrapped in blotting paper sulphite sodium Na2SO3 (this substance is sold in photoshop). Close the bottle stopper, the free end of the venting tube will drop into the glass prepared in advance dilute solution of potassium permanganate KMPO4 (this substance is known in everyday life called potassium permanganate). The solution should be pale pink. When the paper razmoknet of the bottles will be released sulfur dioxide. It reacts with potassium permanganate solution and discolor it.

If you fail to buy sodium sulfite, then replace it with the contents of a large Chuck of conventional photodeveloper. However, in this case, the sulfur dioxide will be an admixture of carbon dioxide, but the experience is not hurt.

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986

 

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