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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: johnnyjohn993 on October 20, 2014, 06:33:41 AM

Title: determination of the chemical formula
Post by: johnnyjohn993 on October 20, 2014, 06:33:41 AM

1.375g of Mannitol completely reacted with oxygen thus producing 1.993g CO₂ and 0.9519g water what is the empirical formula of Mannitol.

umm I really don't know where to start. pls help

all i know is the oxygen has a mass of 1.5699g

Title: Re: determination of the chemical formula
Post by: Arkcon on October 20, 2014, 08:51:39 AM

Quote from: johnnyjohn993 on October 20, 2014, 06:33:41 AM

all i know is the oxygen has a mass of 1.5699g

Really?  That's pretty good.  How did you get that number.  Begin with a balanced reaction.  You don't know the formula for a reactant, so put a place holder [mannitol].  But can you see where the carbon dioxide and what came from?  How much carbon and hydrogen is that?  Careful, mannitol may provide some of its own oxygen.

Title: Re: determination of the chemical formula
Post by: johnnyjohn993 on October 22, 2014, 03:45:17 AM

I got the answer now, I use the mole concept that is, our reactant have the same total amount of mole to the sum of the moles of the the product :D cool :D