Introduction: The initial purpose of the lab is to extract the most copper out of a given amount of malachite, the ore copper is found in. Metals are naturally found in rock called ore. To extract the metal from the ore two processes take place, smelting and roasting. Roasting is a process in which heat is used to decompose ions that are combined. The reaction for the roasting portion of this lab is. . Another method of extracting a metal from ore is smelting. The process of smelting uses heat and a reducing agent (in this case carbon) to extract the element itself. The reaction for the smelting process in this lab is.
Hypothesis: Two initial hypotheses can be made. The first one is predicts the mass of CuO, shown in the work below.
The predicted mass of CuO is 0.72g.
The second hypothesis is the theoretical yield of copper from the second reaction. As demonstrated below –
Materials and Equipment: (From Handout)
1.00g Cu2(OH)2CO3 copper(II) carbonate basic 0.50g C carbon black
ring stand with ring clamp and clay triangle crucible and lid
crucible tongs 2 weigh boats
glass stir rod metal spatula
gas burner and hose igniter
50 ml beaker hot plate
Procedure (from handout)
1. Mount an iron ring on a ring stand, equip with a clay triangle and obtain a Bunsen burner, crucible and cover. Record the mass of the crucible.
2. Add 1.00 grams of copper(II) carbonate basic to the crucible. Place the crucible on the clay triangle and put the cover on, slightly tilted. Begin heating slowly, gradually increasing the temperature until there is evidence of a reaction. When the color change is complete, allow the crucible to cool to room temperature and re-mass. Record the mass of the CuO product and crucible in your data table.
1. While the contents are cooling, measure out 0.50 gram of carbon black. Add the carbon black to the cooled contents of the crucible, mix together thoroughly using a clean, dry stirring rod. Be sure to scrape off any solid that clings to the stirring rod back into the crucible.
2. Return the crucible to the clay triangle and begin heating again. When evidence of a chemical reaction appears, watch carefully. (You should hold the crucible cover with crucible tongs to better observe the process. If particulate matter is emitted, cover quickly.) Heat strongly for 5 more minutes. Then turn off the burner, and using tongs, quickly pour the contents of the crucible into a 50 mL beaker containing 40 mL water. (You may need to scrape the crucible with the spatula to free some of the material.
3. Decant the water carefully. Rinse the product with water and decant carefully two more times. Place the beaker with product on a hot plate set at 4-5 in order to dry the beaker and product. Monitor carefully until the beaker and product are completely dry. Determine and record the mass of beaker and product in your data table.
Mass of Empty Crucible
Initial Mass of Cu2(OH)2CO3
Mass of CuO
Mass of 50 mL Beaker
Mass of CuO and Crucible
Mass of Cu and Beaker
Mass of Recovered Cu
– Theoretical Yield of CuO
To find the theoretical yield, first convert to moles, then multiply the number of moles by the molar ration – in this case 2-1. Then multiply that initial number by the molar mass to attain the theoretical yield in grams.
– Theoretical Yield of Cu.
* To attain this figure, first we convert to moles, then we multiply the number of moles by the molar ratio – in this case it’s 2:2, then we multiply by the molar mass to convert back to grams.
– Percent Yield of CuO
* To find the percent yield we took our actual mass from stochiometric calculations and divided it by our theoretical mass.
– Percent Yield of Cu
* To find the percent yield of the copper we took our actual yield and divided by the theoretical yield derived from stochiometric calculation.
* Yes this method for the most part was efficient however, I do think that the actual transfer from the crucible into the beaker of water and when removing the carbon copper was lost thus lowering the percent yield.
Conclusion: The copper initially was in fact pure copper. By comparing it to the samples by making qualitative observations we concluded that the copper recovered did share many properties hence making it pure copper. The most likely location of error occurred towards the end of the procedure during the transfer of the copper from the crucible to beaker and the removal of carbon. For the most part there really isn’t anyway to eliminate error. Mainly because the error most likely occurred when the copper wasn’t quite a solid so if we had waited for the crucible to cool and transfer then we would of lost even more copper.