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Topic: Recrystallization  (Read 2952 times)

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Offline phthiriasis

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Recrystallization
« on: February 10, 2009, 04:45:09 PM »
A 330g sample of a saturated solution of KNO3(s) in water is prepared at 25.0 degrees C.
If 50g H2O is evaporated from the solution at the same time as the temperature is reduced from 25.0 to 0.0 degrees C, what mass of KNO3(s) will recrystallize?

i have no idea where to start.. it refers me to a graph which shows the g solute/100g h2o vs temperature.. and it looks like there is 15g kno3/100g h2o at 0 degrees and 37ish g at 25 degrees.. but i dont know what to do with this information

**edit**
sorry, i figured it out.. answer was 63g
« Last Edit: February 10, 2009, 04:56:08 PM by phthiriasis »

Offline sjb

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Re: Recrystallization
« Reply #1 on: February 10, 2009, 04:53:05 PM »
A 330g sample of a saturated solution of KNO3(s) in water is prepared at 25.0 degrees C.
If 50g H2O is evaporated from the solution at the same time as the temperature is reduced from 25.0 to 0.0 degrees C, what mass of KNO3(s) will recrystallize?

i have no idea where to start.. it refers me to a graph which shows the g solute/100g h2o vs temperature.. and it looks like there is 15g kno3/100g h2o at 0 degrees and 37ish g at 25 degrees.. but i dont know what to do with this information

thanks for any h.elp (lol) -.-

If a saturated solution of nitre is 37 g solid / 100 g water how much water do you need for 330g?

What is 50 g less than the amount you have previously calculated?

How much nitre can you dissolve in the second amount of water?

So how much can crash out?

S

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