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A solution of copper(II) sulfate that contains 15.00% CuSO4 by mass has a density of...

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lak-86 | Student, Undergraduate | Salutatorian

Posted July 9, 2013 at 6:57 AM via web

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A solution of copper(II) sulfate that contains 15.00% CuSO4 by mass has a density of 1.169 g/mL. A 25.0 mL portion of this solution was reacted with excess concentrated ammonia to form a dark blue solution. When cooled, filtered and dried, 6.127 g of a dark blue solid were obtained. A 0.195 g sample of the solid was analyzed for ammonia by titrating with 0.1036 M hydrochloric acid solution, requiring 30.63 mL to reach the equivalence point. A 0.150 g sample was analyzed for copper (II) by titrating with 0.0250 M EDTA, (which reacts with Cu2+ in a 1:1 ratio). The endpoint was reached after 24.43 mL of the EDTA were added. A 0.200 g sample was heated at 110 ˚C to drive off water, producing 0.185 g of the anhydrous material.


a. Determine the molarity of Cu2+ ions in the original solution.

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted July 9, 2013 at 7:34 AM (Answer #1)

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Molar mass of `CuSo_4` = 159.6g/mol

 

It is given that the density of the solution is 1.1169g/ml

Let us say we have 1L of solution.

Mass of the `CuSO_4` of the solution `= 0.15xx1.1169xx1000 = 167.535`

 

Amount of moles of `CuSO_4 = 167.535/159.6 = 1.05`

So we have 1.05 moles in 1L of solution.

 

So the molarity of Cu^(2+) in the original Solution is 1.05M

 

 

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