Preparation of Ammonium copper (II) sulphate

214528375 29/2/2016

Tevin Krishna

Practical Report 1

Practical Report 1: Preparation of double salt Ammonium Copper(II) Sulphate Introduction: In the experiment that was performed a double salt from a mix Ammonium sulphate and copper(II) sulphate pentahydrate in water that was heated to create a double salt. A double salt is a salt that contains two distinct salts when dissolved but crystallises as a single substance, they contain more than one cation or anion. They usually form larger crystals than the constituents of the double salt. A well know double salt that serves as a cleaner, a laxative and helps with relief of cramps is Epsom salt or Magnesium Sulfate. Ammonium Copper(II) Sulphate hexahydrate, which has blue crystals. It has a square pyramidal molecular geometry (Morosin, 1969).

Reagents and Chemicals:  

Ammonium Sulphate Copper(II) Sulphate Pentahydrate

Experimental Procedure 1g of ammonium sulfate and 2g of copper(II) sulfate pentahydrate were combined in 5ml of distilled water in a 100ml beaker, the mixture was gently heated on a hotplate, the solution was stirred while on the hot plate until the solid dissolved. When all of the solids were dissolved the solution was removed from the hotplate and placed on a tile to reach RT and then placed into in an ice bath for 5 min. Once the crystals formed, a vacuum system was constructed and the crystals were filtered, and transferred to two pieces of filter paper and left to dry. The filtrate that was in the Bϋchner flask was transferred to a beaker and placed on a hotplate and half of the filtrate was evaporated, it was then cooled under tap water and placed on a tile to allow crystals to form. The crystals were filtered and left to dry. Both samples were weighed and placed into sample bags and handed in.

214528375 29/2/2016

Tevin Krishna

Practical Report 1

Calculation of Expected Yield CuSO4.5H2O(aq) + (NH4)2SO4(aq)→CuSO4 (NH4)2SO4. 6H2O Limiting Reagent: Amonium Sulphate Mass used: Ammonium sulphate = 1g, copper(ii) sulphate pentahydrate = 2g,1+2=3g Molar Mass: Ammonium sulphate = 132.14 g/mol Copper(ii) sulphate pentahydrate = 249.58 g/mol Moles: n= =

m M

1 g ( 132.14 ) g/ mol

= 0.0075677 mol

Therefore, by reaction stoichiometry, and the above balanced equation the theoretical moles for CuSO4 (NH4)2SO4. 6H2O would be 0.0075677 g/mol Molar mass of CuSO4 (NH4)2SO4. 6H2O: 399.84g/mol (https://www.americanelements.com, 2016) Expected mass: m n= m = n × M = 0.0075677 mol × 399.84g/ mol M

= 3.03 g

Percentage Yield Mass of actual yield = % Yield

1.52g

= (mass of actual yield/mass of theoretical yield) x 100 =( 1.52g /3.02g) x 100 = 50.3 %

214528375 29/2/2016

Tevin Krishna

Practical Report 1

Discussion In the experiment the formation of the double salt Ammonium copper (II) sulphate hexahydrate was observed after the dissolving of the two reagents the solution took on a blue colour due to the formation of Cu+ ions in the solution. The double salt formed larger blue crystals than the crystal size of its constituents, a usual characteristic of a double salt. The actual yield of this product is just more than half of the theoretical yield which can be attributed to errors such as time spent on the heat plate, and excess evaporation of the second heating of the filtrate, not enough time for crystallisation could also add to lower than theorised yield gained. The resulting double salt that has colour range of bright blue to light blue, light blue being the second filtration and bright blue the initial filtration.

Conclusion In conclusion the actual yield was above half of the theoretical yield, the crystals in the double salt range from light blue to bright blue and the double salt is soluable in water.

References https://www.americanelements.com/ammonium-cupric-sulfate-hexahydrate13587-26-3