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Chemistry / Re: Is there an easy (cheap) way to identify aluminium alloys?
« on: 21/02/2018 16:19:45 »
I agree with ↑. Often the cheapest, simplest way to answer such a question, is to pay someone who has the means to answer it!
However, I will also recommend some simple chemical tests, for the sake of DIY folks. NOTE: While "simple" these methods are NOT SAFE unless proper precautions are taken. I will be discussing the use of some highly corrosive and some mildly toxic substances. Eye protection and gloves are a must! The reactions will also release heat and flammable gasses (also possibly splashing the corrosive contents, so use vessels > 5x bigger than the solutions they contain).
By dissolving known quantities of the metal in question in either acid or base you can learn a fair amount about what's in it (I would recommend a gram or two of metal to begin with--larger quantities will give more precision in determining the composition, but danger scales non-linearly with size--if you double the size of your reaction, it is wise to treat it as 4x as dangerous etc.)
Aluminum will react with concentrated solutions of sodium hydroxide in water (20 grams of NaOH dissolved in 80 mL water), as will zinc, and probably silicon. Magnesium, nickel, copper and iron will not react with this alkaline solution, and will remain as solid precipitates (note, these precipitates may be quite flammable, even pyrophoric, when dry KEEP THEM WET--see Raney nickel: https://en.wikipedia.org/wiki/Raney_nickel)
Aluminum, zinc, magnesium and iron will all react with concentrated solutions of hydrochloric acid (add 30 mL of concentrated HCl, sometimes called muriatic acid, to 70 mL water). This will leave nickel, copper, and silicon behind.
In each case you can separate out the precipitates (by filtration or centrifugation, or just decanting.) KEEP THEM WET! They can then be dissolved using nitric acid. The species in solutions (original and dissolved precipitates) can be determined by reaction with chemical indicators (such as 2,10-phenanthroline) or by using solubility profiles to selectively precipitate out salts of each metal.
Neutralize all acid and base solutions before discarding them. Never mix nitric acid with organic compounds.
AGAIN: DON'T TRY any of this until you have done your research, figure out how to protect yourself (and your friends, family, pets, neighbors etc.) and have a plan for executing the experiments, as well as contingency plans for spills and fires (be prepared!)
However, I will also recommend some simple chemical tests, for the sake of DIY folks. NOTE: While "simple" these methods are NOT SAFE unless proper precautions are taken. I will be discussing the use of some highly corrosive and some mildly toxic substances. Eye protection and gloves are a must! The reactions will also release heat and flammable gasses (also possibly splashing the corrosive contents, so use vessels > 5x bigger than the solutions they contain).
By dissolving known quantities of the metal in question in either acid or base you can learn a fair amount about what's in it (I would recommend a gram or two of metal to begin with--larger quantities will give more precision in determining the composition, but danger scales non-linearly with size--if you double the size of your reaction, it is wise to treat it as 4x as dangerous etc.)
Aluminum will react with concentrated solutions of sodium hydroxide in water (20 grams of NaOH dissolved in 80 mL water), as will zinc, and probably silicon. Magnesium, nickel, copper and iron will not react with this alkaline solution, and will remain as solid precipitates (note, these precipitates may be quite flammable, even pyrophoric, when dry KEEP THEM WET--see Raney nickel: https://en.wikipedia.org/wiki/Raney_nickel)
Aluminum, zinc, magnesium and iron will all react with concentrated solutions of hydrochloric acid (add 30 mL of concentrated HCl, sometimes called muriatic acid, to 70 mL water). This will leave nickel, copper, and silicon behind.
In each case you can separate out the precipitates (by filtration or centrifugation, or just decanting.) KEEP THEM WET! They can then be dissolved using nitric acid. The species in solutions (original and dissolved precipitates) can be determined by reaction with chemical indicators (such as 2,10-phenanthroline) or by using solubility profiles to selectively precipitate out salts of each metal.
Neutralize all acid and base solutions before discarding them. Never mix nitric acid with organic compounds.
AGAIN: DON'T TRY any of this until you have done your research, figure out how to protect yourself (and your friends, family, pets, neighbors etc.) and have a plan for executing the experiments, as well as contingency plans for spills and fires (be prepared!)
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