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UNIVERSITI TUNKU ABDUL RAHMAN FACULTY OF SCIENCE DEPARTMENT OF CHEMICAL SCIENCE PERAK CAMPUS UDEC 1134 CHEMISTRY LABORATORY I BACHELOR OF SCIENCE (HONS) CHEMISTRY Name CHENG HAN XIAN ID no. 1503258 Name of lab partners& ID.no CHONG CHAN YONG 1500601 TEOH SHENG KEAT 1504422 Experiment No. 8 Title of experiment Preparation and studies of potassium tri(oxalato)aluminate(III)trihydrate Date of experiment 28/03/2017 Practical Group P5 Practical Subgroup Group 6 Lecturer Name MS. CHANG CHEW CHEEN
Results and calculations: Mass of Al 2 O 3 .18H 2 O: 3.3095 g Mass of oxalic acid dehydrate: 1.0081 g Mass of potassium oxalate monohydrate: 1.4741 g Mass of filter paper: 0.2864 g Mass of product + filter paper: 1.8230 g Mass of product 1.5384 g From equation Moles of H 2 C 2 O 4 = (1.0081 g / 126.07 g/mol) = 0.0079964 mol 2Al(OH) 3 + 3C 2 O 4 2- + 3H 2 C 2 O 4 2[Al(C 2 O 4 ) 3 ] 3- + 6H 2 O 3 moles of C 2 O 4 2- produce 2 mole of [Al(C 2 O 4 ) 3 ] 3- Number of mole of K 3 [Al(C 2 O 4 ) 3 ] . 3H 2 O = 0.0079964 mol x 3 2 = 0.0053309 mol Mass of K 3 [Al(C 2 O 4 ) 3 ] . 3H 2 O = 0.0053309 mol x 462.3744 g/mol = 2.4649 g Percentage yield = (1.5584 g/ 2.4649 g ) x 100% = 63.22 % Qualitative analysis: Tests Observation Test for potassium Purple flame is produced. Test for aluminium Product + NaOH : precipitate disappeared after NaOH added Product + NaOH + HCl : white precipitate was formed while added NaOH and redissolved after excess NaOH was added. Test for oxalate: Oxalate with H 2 SO 4 : purple solution turn colourless Oxalate without H 2 SO 4 : purple solution remained the same
Discussion: Aluminum (atomic number = 13) is present in the third period and contains empty 3d orbitals and favours the formation of complexes with six coordination number. It forms stable octahedral complexes with ligands such as 8-hydroxyquinoline which also known as “oxine” (C 9 H 7 NO) and with the oxalate anion (C 2 O 4 2- ). [ CITATION Dep17 \l 1033 ]

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