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June 24 2011 6 24 /06 /June /2011 12:51

I have compiled a list of sources for the elements that are available to the amateur chemist. Phosphorus will be discussed here.

 

Phosphorus comes in several allotropes. One is a white, waxy, pryophoric, highly toxic substance. Another is a crumbly, red, flammable substance. Another is a hard, violet, crystalline substance. The first two are most common. White phosphorus (as the white allotrope is called) is used in smoke bombs and incendiary devices. Red phosphorus is used in pyrotechnics and matches. Phosphates are used in toothpastes, baking powder, and cleaners, to name a few.

 

In element form: Armstrong's mixture, found in noisy toy guns that do not shoot anything, is a mixture of red phosphorus and potassium chlorate. Red phosphorus is also found in the striker portion of safety matches. Phosphor bronze has about 1% phosphorus in it.

 

In compound form: Baking powder has phosphates in it. Some rodent poisons use phosphides. Phosphoric acid is found in soft drinks. Phosphorus sulfide is found in the heads of strike-anywhere matches.

 

Here is my sample of phosphorus.  It is scraped from a matchbox striker. Because it was an old matchbox, there appears to be much more phosphorus on it.

 

Phosphorus

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June 23 2011 5 23 /06 /June /2011 12:03

Warning: Nitric acid is very corrosive and toxic. Do not contact it or let it contact any organic materials. The fumes produced are highly toxic. Do not inhale them.

 

You will need:

 

One or more of these: lithium, calcium, magnesium, aluminium, zinc, iron, nickel, tin, lead, copper, silver, gold

Dilute nitric acid

Lots of test tubes

 

For consistency, all of the metals should be about the same shape and size. Zinc powder will react more vigorously than an aluminium chunk, even though aluminium is higher on the reactivity series.

 

In an earlier post (http://lanthanumkchemistry.over-blog.com/article-reactivity-series-demonstration-part-2-77468092.html), I showed the reactivity series by immersing metals in hydrochloric acid (well, lithium floated) and observing their reaction. The corrosion is not observable for all metals, so nitric acid, as an oxidizing acid, will increase the number of metals able to dissolve. Aqua regia, a mixture of nitric and hydrochloric acids, is even stronger, but it does not dissolve silver because a passivating layer is formed.

 

Place nitric acid in all of the test tubes. Add the metals. Here the fun starts. The more reactive metals such as magnesium, calcium, zinc, aluminium, and lithium will release plain old hydrogen gas. The less reactive metals, though, such as copper, iron, lead, tin and nickel will begin releasing nitric oxide gas, which oxidizes to the brown choking nitrogen dioxide. Even silver dissolves, although gold is untouched. If you are using your silver jewelry, take it out before it completely dissolves in the nitric acid.

 

The End

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June 23 2011 5 23 /06 /June /2011 11:57

I have compiled a list of sources for the elements that are available to the amateur chemist. Silicon will be discussed here.

 

Silicon is a hard, bluish-gray semimetal. When extremely pure, it has a mirror-like shine. It is the second most abundant element in the earth's crust. It is used extensively in electronic devices. Many of its compounds exhibit typical semimetal properties; for example, the fluoride is a gas at room temperature.

 

In element form: Transistors and integrated circuits use silicon. Diodes contain silicon, which can be obtained by cracking the ceramic case off and breaking apart the diode via the wires.

 

In compound form: Silicon dioxide is found in sand and quartz. Most rocks are silicates.

 

This is my sample of silicon. It is one half of a cracked open diode after the wire has been cut off. The copper base is visible around the edges, while the silicon crystal is clearly seen.

 

Silicon

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June 22 2011 4 22 /06 /June /2011 13:14

Warning: Hydrochloric acid is corrosive. Do not contact. Some of the metal-acid reactions are quite violent. Wear sufficient protection and conduct experiment in a safe place.

 

You will need:

 

One or more of these: lithium, calcium, magnesium, aluminium, zinc, iron, nickel, tin, lead, copper, silver, gold

Hydrochloric acid, concentrated

Lots of test tubes

 

For consistency, all of the metals should be about the same shape and size. Zinc powder will react more vigorously than an aluminium chunk, even though aluminium is higher on the reactivity series.

 

In an earlier post (http://lanthanumkchemistry.over-blog.com/article-reactivity-series-demonstration-part-1-77387937.html), I showed the reactivity series by immersing metals in water and observing their reaction. The corrosion cannot be observed in a reasonable time span, so using hydrochloric acid instead of water should help. Hydrochloric acid should dissolve the passivating oxide layer, allowing the true reactivity of the metals to be seen.

 

Add hydrochloric acid to all the test tubes. Drop all of the metals in, starting with gold. Gold, silver, and copper have no reaction. Lead has an extremely slow to nonexistent reaction. Tin slowly reacts, releasing hydrogen gas bubbles occasionally. Nickel reacts a bit more noticeably, producing a measurable amount of hydrogen. Iron reacts quite noticeably. Zinc reacts vigorously, producing much heat. Aluminium reacts even more vigorously. Magnesium reacts even more vigorously. Calcium reacts even more vigorously. Lithium reacts even more vigorously. This trend is only observed when all acids are equal concentration and all elements are of equal shape and size.

 

Keep in touch for Part 3!

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June 22 2011 4 22 /06 /June /2011 13:10

I have compiled a list of sources for the elements that are available to the amateur chemist. Aluminium will be discussed here.

 

Aluminium is a very common, light, silvery gray metal. It requires much energy to extract from its ores and can be recycled economically. It is used in many structural applications. Aluminium compounds are used to purify water and deodorize.

 

In element form: Many objects, such as aluminium foil, are made of aluminium.

 

In compound form: Some deodorants have aluminium chloride or oxychloride in them. Emery is made of aluminium oxide.

 

Here is my sample of aluminium. It is a piece of aluminium foil that is crumpled.

 

Aluminium

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June 21 2011 3 21 /06 /June /2011 17:13

Warning: The lithium hydroxide produced when lithium reacts with water is caustic. Do not contact. Only the lithium and the calcium cannot be recovered unharmed form the water. 

You will need:

 

One or more of these: lithium, calcium, magnesium, aluminium, zinc, iron, nickel, tin, lead, copper, silver, gold

Water

Lots of test tubes

 

For consistency, all of the metals should be about the same shape and size. Zinc powder will react more vigorously than an aluminium chunk, even though aluminium is higher on the reactivity series.

 

There is a series called the reactivity series. It ranks the metals from most reactive to least reactive. The most reactive elements react with water, oxidizing acids, and nonoxidizing acids. They are isolated by electrolysis. The second group reacts with oxidizing and nonoxidizing acids. They can be isolated by a carbon reduction. The third group reacts only with oxidizing acids. They are very easy to isolate. The list of metals above is ranked in the order of the activity series.

 

Add warm water to all of the test tubes. Add the metals, starting with gold. Gold and silver have absolutely no reaction. Copper and lead very slowly corrode because of the dissolved oxygen in the water (not because of the water), both forming a protective layer that inhibits further corrosion. Tin and nickel do not react. Iron and zinc corrode a little more readily, although zinc forms a partially protective layer. This is still corrosion by the dissolved oxygen, not by the water itself. Aluminium has a tough protective layer, making it completely unreactive. Magnesium has a protective layer not as strong as aluminium. Since magnesium is so high on the reactivity series, it is corroded by water itself, not by the dissolved oxygen in water. Small hydrogen bubbles can be seen escaping from the magnesium. Calcium forms an incomplete protective layer, but still reacts quite vigorously with water. Lithium, the highest on the reactivity series, forms no protective layer and (if it is not covered in oil) reacts instantly and vigorously with water.

 

The nature of the oxide (crumbly or adhesive) affects the reactivity of the metal as well as its placement on the reactivity series. The oxide layer can be removed by treatment with hydrochloric acid and the true reactivity of the metal can be seen.

 

 

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June 21 2011 3 21 /06 /June /2011 14:02

I have compiled a list of sources for the elements that are available to the amateur chemist. Magnesium will be discussed here.

 

Magnesium is a light, relatively strong alkali metal. It is highly reactive but protected by an oxide layer. It finds much use in high-performance alloys that need to be light but strong. It is also used in pyrotechnics. Magnesium compounds are used as antacids, bath salts, and refractories.

 

In element form: Magnesium fire starters contain magnesium. Magnesium ribbon is easily obtained as well. Fresh water boat anodes are made of magnesium. Laptop frames, some car frames, and expensive pencil sharpeners are made of magnesium alloy.

 

In compound form: Epsom salts are made of magnesium sulfate. Milk of magnesia is made of magnesium hydroxide. Magnesium carbonate is used to make better grip when rock climbing.

 

Here is my sample of magnesium, a fire starter.

 

    DSCF9887.JPG

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June 20 2011 2 20 /06 /June /2011 12:51

Warning: Copper(II) salts are toxic. Do not eat or drink.

 

You will need:

 

Copper sulfate

Sodium chloride

Aluminium foil

 

Copper forms a chloro complex with sodium chloride as well. This chloro complex, as we saw before, is reactive toward aluminium.

 

Dissolve the copper sulfate and sodium chloride in water. Add a piece of aluminium foil to each solution. On the copper sulfate side, you may see a slow reaction. Mix the solutions by pouring one into the other. This will form the green copper chloro complex instead of the hydrated copper complex. The aluminium will start bubbling and dissolving faster.

 

You can try making bromo complexes as well and testing their reactivity. Use sodium bromide instead of sodium chloride.

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June 20 2011 2 20 /06 /June /2011 12:45

I have compiled a list of sources for the elements that are available to the amateur chemist. Sodium will be discussed here.

 

Sodium is a light, low-melting, reactive metal. It belongs in the alkali metals group. It oxidizes rapidly in air, and its reaction with water is famous. It is one of the most widespread metals in the form of its compounds. Sodium chloride is the most well-known sodium compound. Sodium metal has a few specialized uses, such as a coolant in some nuclear power plants.

 

In element form: Low pressure sodium vapor lamps have pure sodium metal in them. High pressure sodium lamps have sodium amalgam in them.

 

In compound form: Sodium chloride is the most common sodium compound. Baking soda also contains sodium, as do many other chemicals.

 

Here is my sample of sodium in the form of one of its compounds, sodium bromide.

 

 Sodium-bromide.JPG

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June 17 2011 6 17 /06 /June /2011 15:45

The Compact Fluorescent Lamp (CFL) contains several elements.

 

Mercury-vapor in the tube

Silicon-solid in the diodes

Aluminium-in the base

Argon-in the tube

Tungsten-in the filaments

Copper-circuit board wires

 

Barium oxide-coating the filaments

Strontium oxide-coating the filaments

Yttrium oxide-in the phosphor

Lanthanum phosphate-in the phosphor

Europium oxide-phosphor dopant

Terbium phosphate-phosphor dopant

Cerium phosphate-phosphor dopant

Silicon dioxide-circuit board construction

Sodium calcium silicate-glass tube

 

It is recommended to collect a different substance for each element. For example, do not have a neodymium magnet represent nickel (from the plating), neodymium, iron, and boron. You will have a bor(on)ing element collection that way.

 

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