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Mystery 'Cakey' red precipitate structure formed in vanadium practical Watch

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    I am a first year undergraduate and in my inorganic module we have recently undertaken a practical to find out various oxidation states of Vanadium. To start we made a stock solution by dissolving 2g of ammonium metavanadate (V) with 1.0 mol.dm-3 20 cm3 of sodium hydroxide. This we then added 35.0 cm3 sulphuric acid (1.0 mol.dm-3 ) and made the volume up to 250cm3 with deionised water. It was after the addition of the sulphuric acid that we observed the yellow solution and a red/brown precipitate/solid that then settled to the bottom of the volumetric flask. The solution was meant to be yellow with none of this precipitate so our initial thoughts are that a salt has been formed but to no avail have we found out what it is. Does anyone have any ideas of what was formed?
    Thank you in advance !
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    (Original post by Jeannette98)
    I am a first year undergraduate and in my inorganic module we have recently undertaken a practical to find out various oxidation states of Vanadium. To start we made a stock solution by dissolving 2g of ammonium metavanadate (V) with 1.0 mol.dm-3 20 cm3 of sodium hydroxide. This we then added 35.0 cm3 sulphuric acid (1.0 mol.dm-3 ) and made the volume up to 250cm3 with deionised water. It was after the addition of the sulphuric acid that we observed the yellow solution and a red/brown precipitate/solid that then settled to the bottom of the volumetric flask. The solution was meant to be yellow with none of this precipitate so our initial thoughts are that a salt has been formed but to no avail have we found out what it is. Does anyone have any ideas of what was formed?
    Thank you in advance !

    I would think you're making V2O5.

    all the ingredients are there and Vanadium is in the correct oxidation state, also, read the section here on acid base reactions of V2O5

    https://en.wikipedia.org/wiki/Vanadi...base_reactions
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    (Original post by MexicanKeith)
    I would think you're making V2O5.

    all the ingredients are there and Vanadium is in the correct oxidation state, also, read the section here on acid base reactions of V2O5

    https://en.wikipedia.org/wiki/Vanadi...base_reactions
    Thank you! That makes so much more sense now
 
 
 
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