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Determine the value of X and write the correct formula when given a sample of hydrated...

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quinnellow | Student, College Freshman | eNoter

Posted January 2, 2012 at 2:08 AM via web

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Determine the value of X and write the correct formula when given a sample of hydrated cobalt chloride CoCl2* XH2O.

CoCl2 is joined to molecules of H2O. Each molecule of CoCl2 has the same number of water molecules bonded to it. The formula is written as CoCl2 * XH2O for now. X is the number of water molecules. X must be a whole number.

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bandmanjoe | Middle School Teacher | (Level 1) Senior Educator

Posted January 2, 2012 at 2:37 AM (Answer #1)

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The number you are searching for is 6.  The correct formula is CoCl2*6H2O (subscripts, except for the 6 coefficient in front of water).  Cobalt (II) chloride is a deep blue color.  When added to water, or added to a substance that contains water, it turns to a deep rose color.  Since it possesses this color change, it is used as an indicator of the presence of water in dessicants.  The rose-colored hexahydrate is one of the most common cobalt compounds in laboratories.  Cobalt (II) chloride serves as a precursor for the synthesis of other cobalt compounds.  When burned over a flame, it gives a bluish-green color.

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