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Units 1 through 4

What have you learned?

Final Practical Evaluation

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Your Challenge

The Problem:

Pollard’s Paint World, IncPollard’s Paint World, Inc, a specialty paint

manufacturing concern has been contracted by Weso StudiosWeso 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.

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The Specifics

Paint PigmentPaint 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.

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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.

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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.

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Making the Pigment

Na2S K3PO4

0.1 M solutions of the following compounds are available:

When mixed, these reactants will produce a

solid precipitate (the pigment).

Cu(NO3)2 Co(NO3)2

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The Reactions

Co(NO3)2(aq) + Na2S(aq) CoS(s) + NaNO3(aq)

Co(NO3)2(aq) + K3PO4(aq) Co3(PO4)2(s) + KNO3(aq)

Cu(NO3)2(aq) + Na2S(aq) CuS(s) + NaNO3(aq)

Cu(NO3)2(aq) + K3PO4(aq) Cu3(PO4)2(s) + KNO3(aq)

In your groups, decide what color

pigment each of you will produce.

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Your First Challenge

Determine which combination of reactants produces the colored pigment you chose.

Available resources:

Solutions of the four salts;

Well plate.

You have15 minutes

Na2S K3PO4

Cu(NO3)2 Co(NO3)2

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Claims and EvidenceClearly identify the reaction that produces your

assigned pigment and balance it:

Co(NO3)2(aq) + Na2S(aq) CoS(s) + NaNO3(aq)

Co(NO3)2(aq) + K3PO4(aq) Co3(PO4)2(s) + KNO3(aq)

Cu(NO3)2(aq) + Na2S(aq) CuS(s) + NaNO3(aq)

Cu(NO3)2(aq) + K3PO4(aq) Cu3(PO4)2(s) + KNO3(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

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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 2.

3. You will need a percent yield to successfully complete your report.

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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

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Make sure you complete the different parts of your lab report.

Clearly justify your claims with the evidence that you collected.

Complete Your Report

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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

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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