Complex 1: bis(acetylacetonato)copper(Il), [Cu(acac)2] 1. Accurately weigh 0.5 g

Question

Complex 1: bis(acetylacetonato)copper(Il), [Cu(acac)2] 1. Accurately weigh 0.5 g of Cu(NO)2.2H2O and dissolve in 20 mL H2O in a 50 mL conical flask. 2. While stirring, add 2 mL acetylacetone and stir for about 5 minutes. Write down your observations. If no solid forms during this time, you may need to initiate the crystallisation process by scraping the inside walls of the flask with a glass rod and continue stirring until your product crystallises 3. Collect the product by vacuum filtering through a small Gooch crucible (see Figure 7.5). Rinse any remaining solid that may have adhered to the conical flask into the crucible with deionised water. 4. Rinse the product with a small amount of ethanol and suck air through the crystals for several minutes. 5. Weigh the product 6. Show it to your demonstrator and obtain initials on your report sheet. CLEAN UP NOTE: Staining of the Gooch crucible may occur. In this event, please start your clean up with ample time as you may need to soak your crucible in a small amount of ascorbic acid for 5-10 minutes to aid in cleaning it.

Explanation / Answer

Complex 1 is crystallization product of Cu (NO3)2.2H2O & Acetyl acetone which is formed by dissolving Cu (NO3)2.2H2O in Acetyl acetone. When Complex 1 crystal is collected by vacuum filtering as per STEP 3, then some impurities stick to the surface of product crystal. To remove these impurities washing with ethanol is done. In this case, residual water attached to complex 1 crystal also acts as impurity. Washing with ethanol removes these impurities along with water attached to crystal. One added advantage of using ethanol is that any residual ethanol evaporates easily leaving pure crystallized product.

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