The purpose of this practical is to analyze complex ions of Cu. There are two parts, foremost to find the empirical expression of hydrated Cu ( II ) sulfate, and secondly to do other Cu ( II ) complex ions in solution and observe the different colourss.
Many ionic compounds contain H2O molecules in their solid crystals, and called hydrates or hydrated salts or hydrated composites. Harmonizing to CP Chemical Inc, Cu ( II ) sulfate is a big dark-blue farinaceous crystal or bluish crystalline pulverization, and it is toxic, odourless with metallic astringence. Copper ( II ) sulfate can fade out into H2O, and the aqueous solution will be somewhat acidic. It can non fade out into ethyl alcohol ; the denseness of Cu ( II ) sulfate is 2.2844g/cm3, ( CP Chemistry Inc, 1994 ) . When the temperature is in surplus of 150? , Cu ( II ) sulfate will lose H2O and crystalline white pulverization remains, called anhydrous Cu ( II ) sulfate.
Anhydrous Cu ( II ) sulfate is a white solid ; its solution is acidic with annoying olfactory property. It can fade out into H2O and aqueous ethyl alcohol, but it can non fade out into absolute ethyl alcohol, ( CP Chemical Inc, 1994 ) . It ‘s easy to deliquescence for anhydrous Cu ( II ) sulfate in damp air. It can besides turn to black Cu oxide at a high temperature. Anhydrous Cu ( II ) sulfate is an of import stuff to fabricate Cu salts in the chemical industry. Hydrous Cu ( II ) sulfate alterations into anhydrous Cu ( II ) sulfate by the chemical equation:
CuSO4·xH2O ( s ) — & gt ; CuSO4 ( s ) + xH2O ( cubic decimeter ) .
Furthermore, hydrochloric acid is a liquid which is colourless and easy to volatilise with annoying olfactory property. The runing point of concentrated hydrochloric acid is -25? , and the boiling point is 109? , ( Chemistry Safety Data, 2003 ) . It can fade out into H2O and alkaline agent.
MSDS ( 2008 ) stated that ammonia solution is a crystalline liquid with annoying olfactory property and corrosion behavior. It can be decomposed when it met heat and visible radiation, and the boiling point is -77? , ( MSDS, 2008 ) .
Equipment and stuff: crucible, spatula, burner, tongs, electronic balance, stand, paper cartridge holder, desiccators, pipettes, conelike flasks, hydrochloric acid, ammonia solution.
Part A ( Lane, 2009 )
First, a fabric was used to clean the interior of the crucible. A paper cartridge holder was placed in the crucible and both were weighed on the electronic balance. The weight was recorded to 0.01g. Then the crucible and paper cartridge holder were put on the little electric balance. Using the spatula, 3g of Cu sulfate was placed in the crucible and accurately weighed. The burner was illuminated and put under the base. In add-on, the crucible and sample, was placed on the base and heated for 5 proceedingss. Then the crystals were stirred with the paper cartridge holder and the alteration in coloring material was noted. The melting pot was placed inside the desiccators for 5 proceedingss to chill down by the tongs. Furthermore, the melting pot was weighed when it was cool plenty. Some H2O was added to the crucible. Finally, the weight was repeated six times to look into and remain the same after heating.
Part B ( Lane, 2009 )
First, some Cu ( II ) sulfate and H2O were put into 3 conelike flasks and shaken to fade out. Furthermore, the concentrated hydrochloric acid was added into one flask utilizing a pipette. Finally, some ammonia solution was added into a 2nd flask utilizing another pipette and observed. The 3rd flask of ( CuSO4·xH2O ) ( aq ) was used as a coloring material control.
However, there is besides holding some experimental phenomena to discourse. In portion A, reiterating the warming is to do certain the H2O of the hydrated Cu ( II ) sulfate has been driven off wholly. If it is heated excessively strongly, Cu ( II ) sulfate can alter into Cu ( II ) oxide, and a colour alteration is seen from bluish to black solid. The figure of moles of anhydrous Cu sulfate is 1.38 & A ; divide ; 64+32+16-4 = 0.008625g ; the mass of H2O is 23.11-22.33 = 0.78g ; the figure of moles of H2O is 0.78 & A ; divide ; 16+ ( 1-2 ) = 0.043g. The mole ratio between the anhydrous Cu ( II ) sulfate with H2O is 1:4.99, about 1:5. As a consequence, the expression of an-hydrous Cu ( II ) sulfate is CuSO4·5H2O ( s ) .
In portion B, the reactions both have the productions of complex metal ions. During the add-on of chloride ions, the reaction produced tetrachloride Cu ions. Adding the ammonia solution, produces [ Cu ( NH3 ) 4 ( H20 ) 2 ] 2+ which is indigo, ( Clark.J, 2003 ) .
All of two experiments are have their ain consequence. In portion A, the value for the figure of H2O molecule in a Cu ( II ) sulphate crystal was 5 which agree with the given true value. In add-on, in portion B, the reactions were used to do complex ions in solution.
- Chemistry Safety Data, ( 2003 ) [ on-line ] Chemistry Safety Data: Hydrochloric Acid hypertext transfer protocol: //cartwright.chem.ox.ac.uk/hsci/chemicals/hydrochloric_acid.html [ Accessed day of the month 28/12/09 ]
- CP Chemical Inc, ( 1994 ) [ on-line ] Copper Sulphate hypertext transfer protocol: //pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/copper-sulfate-ext.html # top [ Accessed day of the month 28/12/09 ]
- MSDS, ( 2008 ) [ on-line ] Ammonia Solution, Strong hypertext transfer protocol: //www.jtbaker.com/msds/englishhtml/a5472.htm [ Accessed day of the month 28/12/09 ]
- Lane, R ( 2009 ) IFY Lab Handout: Chemistry Practical 2: Complex Ions of Copper ( II )
- Clark, J ( 2003 ) [ on-line ] The forms of complex metal ions hypertext transfer protocol: //www.chemguide.co.uk/inorganic/complexions/shapes.html # top [ Accessed day of the month 05/01/10 ]