lab 3 Calculations(mike)

# lab 3 Calculations(mike) - Decanting was used for the...

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Calculations C(Cu(NO 3 ) 2 ) = .157 m(Cu)theoretical = .157 x .025 x 63.55 = .2494g m(Cu)practical = 60.613 – 60.395 = .218g .218 / .2494 = .87397 x 100 = Results and Discussion 1) It is possible that excess compounds could still be left stuck to the copper. Also, there may have been some water not visible to the eye that could result in a larger mass. 2) .305g x 1 mol Cu x 1mol Cu 3 (PO 4 ) 2 x 380.59 g Cu 3 (PO 4 ) 2 = .609 g 63.55 g Cu 3 mol g Cu 1 mol Cu 3 (PO 4 ) 2 Cu 3 (PO 4 ) 2 When trying to decant the solution, some of the precipitate may have left the solution 3) The phosphate turns into phosphoric acid after HCl is added to the copper phosphate through a chemical reaction. A) After adding 2 ml of concentrated NaOH (6M), the formation of Cu(OH) 2 occurred, producing a turquoise gelatinous solution. Red litmus paper was used to test the basic concentration. The red litmus paper turned blue, therefore, the solution was basic. Precipitate liquid was formed and kept for the next part.
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Unformatted text preview: Decanting was used for the solution. B) Upon adding H 2 SO 4 (3M), all precipitate was dissolved. The color of Cu(OH) 2 turned a light blue/turquoise color after it became diluted with H2SO4. CuSO 4 was formed. C) The addition of NaOH (6M), by dropping, neutralized the excess H2SO4 according to the following equation: 2NaOH + H 2 SO 4-> Na 2 SO 4 + 2H 2 O. 10 ml of Na 3 PO 4 (.5M) was added to the neutralized solution, turning it light blue and into Cu 3 (PO 4 ) 2 . The solution became basic after the addition of 2 ml of NaOH (6M). D) 10 ml of HCl was added to the solution from part C which dissolved the precipitate. The color changed to less diluted blue/turquoise color. E) From the copper(II) chloride solution, the addition of magnesium displaces copper from the copper(II) chloride. Hydrochloric acid dissolves the excess magnesium, creating hydrogen gas, and inducing the transparency of the solution. 87.4% yield...
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## This lab report was uploaded on 04/10/2008 for the course CHEM 112 taught by Professor Jursich during the Spring '08 term at Ill. Chicago.

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