Site for children

HomeResearch fun Chemical experimentsExperiments with tin and lead

EXPERIMENTS WITH TIN AND LEAD

 

Metals are not very convenient for experiments: experiments with them typically require complex equipment. But some experiences can be put in a home laboratory.

Let's start with the tin. Hardware stores sometimes sticks a metal tin for soldering. With such a small ingot, you can do an experiment: take the pewter wand in both hands and bend - you will hear a distinct crunch.

The fact that metallic tin such a crystal structure that bending of the crystals of the metal as would RUB against each other, there is a crunchy sound. By the way, on this basis it is possible to distinguish the pure tin from tin alloys - rod of the alloy when bent no sounds no issues.

And now let's try to extract tin from empty cans of those, which should not be discarded and disposed of. Most cans of tinned inside, i.e., they are covered with a layer of tin, which protects the iron from oxidation, and food products from spoilage. This tin can be removed and reused.

First of all the empty jar should be clean. Regular washing is not enough, so pour in a jar of concentrated solution of washing soda and put it on half an hour on the fire so that the cleaning solution has pricipal as it should. Drain the solution and rinse the jar two or three times with water. You can now consider it pure.

We will need two or three batteries for pocket lantern series-connected; you can take rectifier with transformer or battery 9-12 Century. Whatever the current source to the positive pole attach a tin (watch carefully so that was a nice touch - you can break into the upper part of the banks a small hole and wear it the wire). The negative pole connect with any piece of iron, for example, with a large cleared to Shine nail. Lower iron electrode in a jar so that it does not touch the bottom and sides. How to hang - think for yourself, this simple thing. Pour in the jar of a solution of alkali is caustic soda (be handled very carefully!) or washing soda; the first option is better, but requires extreme accuracy in the work.

As the alkali solution again and again will need to experiment, learn here, how to cook it. Add washing soda Na2CO3 to a solution of slaked lime CA(Oh)2 and boil the mixture. The reaction produces sodium hydroxide NaOH and calcium carbonate, i.e. chalk, practically insoluble in water. This means that in the solution, after cooling, it should be filtered to only include alkali.

But back to the experience with a tin can. Soon on the iron electrode will begin to stand out bubbles of gas and tin from cans will slowly go into solution.

Well, if it is necessary to obtain a solution containing tin, and the metal itself? Well, it's possible. Remove from the solution of the iron electrode and replace it with coal. Here you will again help the old, worn out battery, a zinc Cup which has a carbon rod. Remove it and connect the wire to the negative pole of your power source. On the rod during electrolysis will settle spongy tin, and if the voltage is chosen correctly, then it will happen pretty quickly. However, it may happen that the tin with one of the banks will be enough. Then take another jar, gently cut it into pieces with special scissors for metal and place it inside the banks, into which is poured the electrolyte. Be careful: the crop should not touch the carbon rod!

Assembled on the electrode tin can be melted. Disconnect the power, remove the carbon rod with a sponge tin, put it in a porcelain Cup or a clean metal can and hold on the fire. Soon the tin will merge into dense ingot. Do not touch it until the banks until they have cooled!

Part spongy tin can not be melted, and leave for other experiments. If dissolving it in hydrochloric acid in small pieces and with a moderate heat, then get the solution of chloride of tin. Prepare a solution with a concentration of about 7% and add, while stirring, a solution of alkali slightly greater concentration of about 10%. First, let fall a white precipitate, but he soon dissolves in excess alkali. You got the solution stuns sodium - the one who formed you in the beginning, when you started to dissolve the tin from the tin. But if so, then the first part of the experience - the transfer of metal from banks in the solution can not be repeated, and proceed directly to the second part, when the electrode deposited metal. It will save you a lot of time, if you want to get more tin from cans.

Lead melts easier than tin. In a small crucible or in a metal can under Polish put a few pellets and heat in the flame. When the lead is melted, carefully remove the jar from the heat, taking her over the edge a great reliable tweezers or pliers. Molten lead pour in plaster or metal form or simply in sandy well - so you will get a homemade lead casting. If further ignited molten lead in the air, then after a few hours on the surface of the metal formed a red plaque - mixed oxide of lead; called "minium" it is often used before for the preparation of paints.

Lead, like many other metals, interacts with acids, displacing of them are hydrogen. But try to put the lead in concentrated hydrochloric acid it dissolves. Take another, obviously more than a weak acid is acetic acid. In her lead, though slowly, but dissolves!

This paradox is explained by the fact that interaction with the hydrochloric acid formed poorly soluble chloride of lead PbCl2. Coating the metal surface, it prevents further interaction with acid. But the lead acetate Pb(CH3OO)2, which is obtained by reaction with acetic acid, dissolves well and does not prevent the interaction of acid and metal.

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

 

Your name (nick):
Comment:
Enter the result of the calculation
     

Scientific fun. Home experiments.

  © 2014 All children