http://db.tt/AK7dfXB5 -- Here is the lab procedure What are the \"oxidizable sub
ID: 835565 • Letter: H
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http://db.tt/AK7dfXB5 -- Here is the lab procedure
What are the "oxidizable substances" mentioned in step 7? Where do they come from? How would your results differ if not all of the elemental iron was oxidized to Fe3+, but some remained as Fe2+? How is the oxidation accomplished in this experiment? If the ignition were not completed, how would your results differ? What is the common name for iron (III) oxide? What does "smelt" mean? Why is this a danger in our experiment? What would be the weight% Fe if the sample were pure Fe2O3?Explanation / Answer
1) oxidizable substance means any thing that can be oxidised present on the crucible.
this will allow any substance that might outgas or react with air to do so, and the remaining char (if any) will either be adhered to the crucible or can be quickly scraped off once the crucible have been cooled in a desiccator (careful not to put the hot crucibles inside the desiccator right away, let it cool until placing your hand an inch above the crucible does not indicate a lot of heat being given off - otherwise, it will create a very strong vacuum and will prevent opening the desiccator). The crucibles are now cleaned for gravimetric work since no further oxidation, outgassing, or reaction will be possible for whatever remains inside the crucible.
If all the Fe is not oxidized to Fe3+ , then all the Fe ion will not be precipitated as Fe(OH)3, and hence we will not be able to determine the exact number of Fe present. Oxidation is accomplished by this statement in the lab note :
using highly concentrated HNO3 we ensure complete oxidization.
3) If the ignition doesnt take place nicely then there are chances that whole reaction of converting gelatinous oxide into ferric oxide will be incomplete. More over there is huge chance of filter paper reamined being totally unburned and hence adding impurities to the output, as it has been stated in the experiment that => You may need to ignite longer to get rid of all of the filter paper.
4) Common name is Hematite also called Ferric oxide.
Smelt Means: To melt or fuse (ores) in order to separate the metallic constituents
this is dengourous because melting the ore will be requiring huge heat , and if smelting occurs during the experiment then the crucible will not be able to handle the heat and will burst which may lead to injuries.moreover huge precision and extreme conditions required.
5) %weight of the Fe in Fe2O3 pure sample is = (112/160 )* 100 = 70%.
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