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Offline zeshkani

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quick question
« on: September 01, 2007, 09:15:52 PM »
i just have a quick question iam doing an experiment and it says "dissolved in three-fold excess concentrated HNO3, diluted with
twice its volume of deionized water"  what does this mean, (especially three fold excess)




Offline Borek

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Re: quick question
« Reply #1 on: September 02, 2007, 04:22:51 AM »
What are you dissolving? Most likely you need to write balanced reaction equation, calculate stoichiometric amount of acid - and multiply it by three.
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Offline zeshkani

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Re: quick question
« Reply #2 on: September 02, 2007, 12:08:04 PM »
we are trying to make a superconductor at liquiud nitrogen temps

"Place 3.37 mmol of Y2O3, dissolved in three-fold excess concentrated HNO3, diluted with
twice its volume of deionized water, and evaporated to dryness on the hot plate in a
fumehood; fumes of toxic nitrogen dioxide, NO2, will be liberated). Add 20 mL of deionized
water to the cooled beaker and then add 13.46 mmol of Ba(NO3)2 and 20.19 mmol of
Cu(NO3)2. Rinse any weight boats with minimal deionized water in order to get all of the
precursor powder into the beaker. Dissolve as much as possible of the solids; do not be
concerned if some insolubles remain. Assuming that the final product has the title
stoichiometry, calculate the theoretical number of grams of product and then add 1.3 grams of
citric acid [HOC(CO2H)(CH2CO2H)2] per gram of product to the above solution mixture.
Follow this by 1.1 mL of ethylene glycol (HOCH2CH2OH) per gram of final product."

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