ChemistryForever
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Alkali metals
I have 2 questions:
1) Why are alkali metals normally stored under oil, which has oxygen so they get coated, instead of, let's say, toluene, so they can remain shiny ?
2) If i distill some cesium, would it be safe to be stored under oil just as lithium sodium or potassium?
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j_sum1
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Storage options. There are a few considerations.
You need something inert to your metal. You want something without dissolved water.
You need to think about density. It helps if your metal sinks. This is tricky for Li.
Availability, cost, convenience. I am not sure that toluene has a whole lot of advantage over mineral oil or kerosene.
As for Cs, you just need to be aware that it reacts faster than Na. Same general principles for storage and handling. Just less margin for error. I
recommend doing a bit of research and watching some exemplars before attempting.
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DraconicAcid
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An alkali metal isn't going to get coated any faster in oil than in toluene- oxygen and water have marginal solubilities in both liquids. It's better
to use oil simply because it's not going to evaporate.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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unionised
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What oxygen?
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ChemistryForever
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The oxygen dissolved in the oils. Also I would not find it awkward for rubidium and cesium ( and even probably potassium upon long storage ) to be
even able to degrade a bit the oils taking some oxygen from their molecules and consequently changing their properties.
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walruslover69
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the amount of oxygen dissolved in oil, is compared to the amount dissolved in toluene, kerosene or any other hydrocarbon. It nothing to really worry
about.
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DraconicAcid
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Quote: Originally posted by ChemistryForever  | | The oxygen dissolved in the oils. Also I would not find it awkward for rubidium and cesium ( and even probably potassium upon long storage ) to be
even able to degrade a bit the oils taking some oxygen from their molecules and consequently changing their properties. |
If you're using paraffin oil or mineral oil, there aren't any oxygens in the oil molecules. Or were you thinking of olive oil?
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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unionised
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| Quote: Originally posted by ChemistryForever | | The oxygen dissolved in the oils. Also I would not find it awkward for rubidium and cesium ( and even probably potassium upon long storage ) to be
even able to degrade a bit the oils taking some oxygen from their molecules and consequently changing their properties. |
Do you realise that they don't use cooking oil?
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fusso
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| Quote: Originally posted by unionised | | Quote: Originally posted by ChemistryForever | | The oxygen dissolved in the oils. Also I would not find it awkward for rubidium and cesium ( and even probably potassium upon long storage ) to be
even able to degrade a bit the oils taking some oxygen from their molecules and consequently changing their properties. |
Do you realise that they don't use cooking oil? |
What's the mechanisms and products of alkali metals reacting
with fatty oils? Do esters do pinacol coupling?
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ChemistryForever
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By the way i have another question : at my school ( now i'm at uni  ) they have
an ancient potassium bottle ( i think there is more than half a kilo there ) and i think it is roughly about 50 years old. it has an over a millimeter
of yellow peroxide and superoxide coating, the bottom is virtually a mess, there are tons of oxides and peroxides. They use it tons of times for the
alkali metals + water demonstrations like i'd say 8 times a year when the people who begin studying chemistry learn the basics.
The question is: how did nothing shitty happen ? I heard that old potassium is dangerous cuz it can ignite upon cutting etc. Was that luck, or that is
a fact meant just to scare people?
By the way i have to admit that the ancient bottles were the best. They had there about 1 liter of liquid bromine, and that bottle is i think around
30 years old ( cause almost nobody uses it ). And it is not sealed or something, you can open it. The fact is that that bottle is so vapor proof that
there is no smell of bromine lacking from there, thus it stayed in that bottle for so long. So I'd advice keeping that stuff in old chemistry bottles
if you have access to them, many times they are better
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j_sum1
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Thread Pruned
21-12-2018 at 21:03 |
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