I have compiled a list of sources for the elements that are available to the amateur chemist. Gallium will be discussed here.
Gallium is a soft, low-melting metal. It can even melt in the human hand. Gallium is found beneath aluminium on the periodic table. It is silvery gray, just like most metals. Gallium forms colorless trivalent compounds, similar to aluminium. Gallium is moderately reactive and will dissolve slowly in hydrochloric acid, as well as in strong bases. Gallium forms an alloy with indium and tin that is a liquid at room temperature. This alloy is known as galinstan. Gallium is generally found in small quantities in zinc ores. It forms brittle alloys with zinc, aluminium, and many other metals. Because of this, gallium is classified as a corrosive and is expensive to ship legally.
In element form: Galinstan, an alloy of gallium, indium, and tin, is found in Geratherm mercury-free thermometers.
In compound form: Gallium arsenide is used in high-frequency transistors and ICs, as well as in infrared LEDs. Most other LEDs use gallium compounds in some form or another. The inside of the glass bulb on a galinstan thermometer is coated with gallium oxide to prevent the galinstan from sticking.
Here is my sample of gallium. It is a galinstan splat from a galinstan thermometer. I normally store galinstan under water to prevent it from sticking, but it gets a surface oxide coating under water, making it look dull and shapeless. This galinstan was photographed shortly after removing it from the thermometer.
I have compiled a list of sources for the elements that are available to the amateur chemist. Zinc will be discussed here.
Zinc is a relatively soft, bluish colored metal from Group 12. It is sometimes considered a transition metal and sometimes a post-transition metal. Zinc is a relatively cheap and common metal with strong reducing properties. It is used to protect other metals from oxidation by oxidizing in their place, either as an outer coating or a separate chunk known as a sacrificial electrode. Zinc compounds are colorless and boring. Zinc's reaction with hydrochloric acid is well known. Zinc will react with many metal salts, precipitating the metal and forming a zinc salt. Therefore, zinc's biggest use in home chemistry is a reducing agent.
In element form: Brass has about 30% zinc in it. The casings of carbon-zinc batteries are pure zinc metal. Alkaline batteries contain zinc powder in their centers when fresh. Sacrificial anodes for boats are often made of zinc.
In compound form: Zinc oxide is a common white pigment. Zinc sulfide is used in glow-in-the-dark materials.
Here is my sample of zinc metal. It is a piece of zinc from a battery casing. The inside is kind of corroded, even in fresh batteries. The casing gets thinner as the battery gets depleted.
I heated a chunk of indium to red heat. It initially melted, then seemed to solidify. In fact, the surface developed a skin of indium oxide which prevented the metal from dripping all over. After this skin was formed, there was no more oxidation. I can try heating a piece of thin indium foil and seeing whether it oxidizes more thoroughly. Here is what the indium looked like after heating. The indium is still soft and malleable under the coating.
I have compiled a list of sources for the elements that are available to the amateur chemist. Copper will be discussed here.
Copper is a soft, reddish-pink metal. It is one of the only metals which has a color other than gray or blue-gray. Copper is pinkish when pure and more reddish-brown when exposed to air. Copper is an excellent electrical conductor and is rather inert. It does not dissolve in non-oxidizing acids if oxygen is not present. Copper is necessary for the human body in small quantities but toxic in large amounts. Copper compounds have a wide range of colors, but many are green to blue. When copper corrodes, it turns green, forming a protective patina of copper hydroxides and carbonates. Many interesting experiments can be performed using copper and its compounds.
In element form: Pure copper is used in water pipes and household wiring. Brass contains about 70% copper, bronze about 90%. U.S. nickels are made of 75% copper.
In compound form: Bright green-blue copper(II) chloride can be made by mixing copper metal with hydrogen peroxide and hydrochloric acid and evaporating the green solution obtained.
Here is my sample of copper. It is a piece of pure copper wire (left), a brass antenna (center), and a copper-containing solder (right).
I have compiled a list of sources for the elements that are available to the amateur chemist. Nickel will be discussed here.
Nickel is a hard golden-silver corrosion-resistant metal. It forms green and blue compounds that are predominantly divalent. Nickel can cause allergic reactions, while its salts are considered Category 1 carcinogens (definitely carcinogenic). Nickel is used as a 25% nickel-75% copper alloy in the U.S. nickel. Some Canadian coins are made of pure nickel, which is ferromagnetic (strongly attracted to a magnet).
In element form: Some objects such as magnets are nickel plated. Obtain a pure 100% nickel coin, such as an old Canadian nickel. Precipitate nickel metal from a solution of its ion by reacting it with magnesium. A U.S. nickel is 25% nickel. 18/10 stainless steel has 10% nickel in it. Nichrome has about 80% nickel. Alnico magnets contain from 15-26% nickel. Cheap spark plugs' ground electrodes can be nickel plated or solid nickel.
In compound form: Nickel metal-hydride and nickel-cadmium batteries have nickel oxide hydroxide in them.
Here is an old Canadian coin, made of pure nickel metal.
Nickel is a corrosion-resistant metal from Group 10. It forms predominantly divalent compounds. Here are several ways to dissolve nickel metal.
Hydrochloric acid + hydrogen peroxide: Nickel dissolves with moderate speed in this mixture. This is probably the cheapest and best way to dissolve nickel. However, nickel chloride is deliquescent, so the best way to store nickel would be in an a concentrated chloride solution or as the carbonate.
This picture shows a piece of a spark plug ground wire (made of quite pure nickel) dissolving in this mixture.
Nitric acid: Nickel also dissolves well with this acid mixture. Nitrogen dioxide is produced as well as deliquescent nickel nitrate.
See this video: http://www.youtube.com/watch?v=zGVeDiVilgM as I do not have or care to make nitric acid.
Hydrochloric acid: Nickel dissolves extremely slowly in pure hydrochloric acid.
Sulfuric acid: Nickel can dissolve in hot concentrated sulfuric acid as well.
Acetic acid: 5% acetic acid is too dilute to dissolve nickel metal. Even the addition of hydrogen peroxide did not dissolve the nickel to any appreciable extent after 36 hours.
Iron(III) chloride: Iron(III) chloride acidified with hydrochloric acid easily and quickly dissolves nickel, resulting in a green solution of nickel(II) and iron(II) chlorides. Separation of the two may be done by the formation of a soluble ammine complex with the nickel. This method seems faster than the hydrogen peroxide method, and iron(III) chloride is easily made by dissolving rust powder in hydrochloric acid.
Note: Since my battery is simultaneously wet (squeezing it will make it drip electrolytes) and dry (no beakers full of electrolyte), I will just call it "my cell".
In the past, I had experimented with a variety of cells. My best zinc-copper(II) chloride cell obtained a total voltage of 1.6 volts at 80 milliamps. This was after quite a bit of work and previous trials. Magnesium, which I did not have at that time, is more electropositive than zinc, and should create a higher voltage. I soaked a tissue (which did not soak very well) with dilute copper(II) chloride solution and wrapped it around a fat carbon rod from a D size carbon-zinc battery. I then wrapped a NaCl-soaked tissue around the CuCl2 tissue. A piece of magnesium foil was placed on the outside and the whole assembly was twist-tied together. This battery, which hardly took 5 minutes to assemble and had many problems, produced 1.95 volts at 120 milliamps. Magnesium is a better cathode than zinc when cost is not a concern. I could improve this design by:
The battery was able to run a red LED, which drew 3.0 milliamps.
Pictures will be seen later. Look here for more information about electrochemistry and voltaic cells: http://chemwiki.ucdavis.edu/Analytical_Chemistry/Electrochemistry/Voltaic_Cells
Just this morning I obtained true titanium foil. It is heavier, shinier, and much stronger than magnesium foil. It is also much less reactive; no reaction occurred with a concentrated copper(II) chloride solution. However, my hydrochloric acid is too dilute to dissolve the titanium, so I need to find another method of dissolution.