Chemistry XXI Units 1 through 4 What have you learned? Final Practical Evaluation

Chemistry XXI Your Challenge The Problem: Pollard’s Paint World, Inc Weso Studios Pollard’s Paint World, Inc, a specialty paint manufacturing concern has been contracted by Weso Studios' to make tubes of various colors of oil-based paints. You are assigned to come up with the pigment to be used in one of the paints.

Chemistry XXI The Specifics Paint Pigment More specifically, you are to identify a pigment of the correct color and then determine how to quantitatively make the pigment. Your report to the development team will need to contain a procedure for making 1.0 kg batches of the pigment.

Chemistry XXI PAINT PIGMENT What are they? What do you think makes a good pigment? A colorful chemical compound that won’t change composition over time. Insoluble salts of heavy metals have been popular pigments for thousands of years.

Chemistry XXI Your Pigment For this problem you are asked to identify a chemical compound of the proper color and determine a method for quantitatively preparing it to use as a pigment.

Chemistry XXI Making the Pigment Na 2 SK 3 PO M solutions of the following compounds are available: When mixed, these reactants will produce a solid precipitate (the pigment). Cu(NO 3 ) 2 Co(NO 3 ) 2

Chemistry XXI The Reactions Co(NO 3 ) 2 (aq) + Na 2 S(aq)  CoS(s) + NaNO 3 (aq) Co(NO 3 ) 2 (aq) + K 3 PO 4 (aq)  Co 3 (PO 4 ) 2 (s) + KNO 3 (aq) Cu(NO 3 ) 2 (aq) + Na 2 S(aq)  CuS(s) + NaNO 3 (aq) Cu(NO 3 ) 2 (aq) + K 3 PO 4 (aq)  Cu 3 (PO 4 ) 2 (s) + KNO 3 (aq) In your groups, decide what color pigment each of you will produce.

Chemistry XXI Your First Challenge Determine which combination of reactants produces the colored pigment you chose. Available resources:  Solutions of the four salts;  Well plate. You have 15 minutes Na 2 SK 3 PO 4 Cu(NO 3 ) 2 Co(NO 3 ) 2

Chemistry XXI Expected Results for the color of the precipitates. CoS(s)Co 3 (PO 4 ) 2 (s) CuS(s)Cu 3 (PO 4 ) 2 (s)

Chemistry XXI Claims and Evidence Clearly identify the reaction that produces your assigned pigment and balance it: Co(NO 3 ) 2 (aq) + Na 2 S(aq)  CoS(s) + NaNO 3 (aq) Co(NO 3 ) 2 (aq) + K 3 PO 4 (aq)  Co 3 (PO 4 ) 2 (s) + KNO 3 (aq) Cu(NO 3 ) 2 (aq) + Na 2 S(aq)  CuS(s) + NaNO 3 (aq) Cu(NO 3 ) 2 (aq) + K 3 PO 4 (aq)  Cu 3 (PO 4 ) 2 (s) + KNO 3 (aq) Now, calculate what volume of a 0.1 M solution of each reactant you need to produce 0.25 g of your pigment. You have 15 minutes

Chemistry XXI 1.The precipitate will filter better if you let it “age” first. A minimum of 10 minutes is recommended. 2. You can dry your product using the hot plate IF the setting is not greater than You will need a percent yield to successfully complete your report.

Chemistry XXI Your Actual Challenge Design and carry out a procedure for preparing exactly 0.25 g of your pigment. Available resources:  Solutions of the four salts;  25-mL graduated cylinder;  100-mL beakers;  Funnel and filter paper.  Balance. You have 45 minutes

Chemistry XXI Make sure you complete the different parts of your lab report. Clearly justify your claims with the evidence that you collected. Complete Your Report

Chemistry XXI Here’s how:  You remove everything from your locker and put it on the lab bench. Make sure the inventory is complete and clean the contents.  A prep person will come by and check your locker. When complete that person will give you a “drawer complete” slip.  You take the drawer complete slip to the window to get your receipt (or a bill, if there are charges). You are not done until you have your receipt or bill. Locker Check-Out The written part of the final exam will not begin until everyone is finished with check-out

Chemistry XXI WRITTEN TEST There is not enough room to answer the questions on the test paper. Please answer on separate sheets making sure you identify where each problem is answered. For numerical answers, put a box around the answer. You have one hour. Let’s Finish