Chem Lab 3: Synthesis of K2[Cu(C2O4)2(H2O)2] – Flashcards
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synthesize
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to make
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potassiumdiaquadioxalatocuprate(II)
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K2[Cu(C2O4)2(H2O)2]
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metal complexes
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a type of molecule that consists of a central metal atom covalently bonded to ions or molecules, called ligands; also called "coordination compounds" or "coordination complexes"; common in biological systems
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coordinate covalent bond
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the bond between a metal and a ligand; the ligand donates both electrons to the bond
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heme group
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iron-containing component of hemoglobin, which transports oxygen in the blood
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What is the central atom of the diaquadioxalatocuprate(II) ion?
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copper
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The copper atom is bonded to what?
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2 waters (H2O) and 2 oxalate groups (C2O4 2-) - the water and oxalate groups are the ligands
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What donates the electrons to the covalent bond?
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an oxygen on each group
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monodentate ligands
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ligands that bond to the metal through only one atom; like water
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bidentate ligands
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ligands that bond to metal through 2 atoms; oxalate
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How many ligands in the diaquadioxalatocuprate(II) ion?
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4 - (two H2O + two C2O4 2-)
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How many bonding regions in the diaquadioxalatocuprate(II) ion?
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6 - since the oxalate binds in two places
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octahedral geometry
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the diaquadioxalatocuprate(II) ion, because there are four ligands and six bonding regions
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stoichiometry of the reaction
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a balanced chemical equation indicates the relative amounts of reactants required and the relative amounts of products that will be produced
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an excess of one reactant is added to be sure that the other reactant, the ____ ___, is completely consumed
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limiting reactant
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limiting reactant
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controls (limits) the extent of the reaction because when it has been consumed, the reaction can no longer occur; determines how much product can be produced
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chemical reaction for the synthesis of potassium diaquadioxalatocuprate(II)
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CuSO4 5H2O(aq) + 2K2C2O4H2O (aq) --> K2[Cu(C2O4)2(H2O)2](s) + K2SO4(aq) + 5H2O(l)
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What is heated before mixing?
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solutions of copper (II) sulfate pentahydrate and potassium oxalate monohydrate
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Why is it heated before mixing?
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the solubility of a substance increases with heat; this ensures that the salts are entirely dissolved and able to dissociate
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Why to we allow the solution to slowly cool after mixing?
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this allows the product to very slowly precipitate, because the solubility of the solids decreases as you cool the substance, and form a crystalline structure that reduces impurities
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Why do we place the product in an ice bath?
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to cool it further and to maximize the yield (amount of product we get)
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theoretical yield
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the maximum amount of product that can be produced
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How can the limiting reactant be determined?
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by calculating the theoretical yield of the reaction given the amount of each reactant used; the reactant that gives the lowest theoretical yield is the limiting reactant
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How do you calculate the theoretical yield?
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calculate the number of moles of your product that would be produced if all the reagent in question were converted to the product --> use the molar mass of the reactant to convert grams of reactant to moles of reactant, and then use the stoichiometry of the balanced chemical reaction to convert moles of reactant to moles of product, and finally use the molar mass of the product to determine the mass of the product that would be theoretically produced
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percent yield
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(experimental yield / theoretical yield) x 100%
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experimental yield
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the amount of product actually produced, which you find by massing your product; should always be less than the theoretical yield
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Why should the experimental yield be less than the theoretical yield?
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(1) issues with the the experimental design that can make it difficult to transfer all your crystals (2) production of side products (3) small amounts of of material typically remain in the solution and do not precipitate out
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side products
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in this case, and copper-containing products other than the product
