- Количество слайдов: 19
Gen. Chem 14 th Class Today’s Agenda: v Collect pre-lab assignment. Final Exam v Locker Check-out. v Conduct written test of course material. v Review background material on paint pigments. v Discuss the problem to be addressed. v Collect data. v Analyze results. v Write and submit a report.
LOCKER CHECK-OUT Gen. Chem Before we do anything else, the preproom people will check you out of your locker. Here’s how. v You remove everything from your locker and put it on the lab bench. Make sure the inventory is complete and clean the contents to the best of your ability. v A prep person will come by and check your locker. When complete that person will give you a “drawer complete” slip. v 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. No testing will begin until everyone is finished check-out
Gen. Chem THE WRITTEN HALF 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.
The Practical Problem: Gen. Chem Adamowicz Artisans, Inc, a Artisans, Inc specialty art materials supplier has been contracted by Weso Studios' to make tubes of Studios various colors of oil-based paints. You are assigned to come up with the pigment to be used in one of the paints.
Gen. Chem The Specific Problem: 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.
Let′s think! Gen. Chem PAINT PIGMENT What are they? How do you make one?
Gen. Chem PIGMENT A chemical compound that won’t Putting the color into change composition over time. paint. What do you think makes a good pigment? Insoluble salts of heavy metals have been popular pigments for thousands of years.
Your Pigment Gen. Chem For this problem you are asked to identify a metal salt of the proper color and determine a method for quantitatively preparing that salt to use as a pigment.
Gen. Chem Let′s think! Making the Pigment Solutions of the following seven salts are available. Na 2 S Na 2 CO 3 Cu(NO 3)2 K 3 PO 4 Co(NO 3)2 NH 4 OH Fe(NO 3)3 In your groups Predict the salts that are likely to precipitate when these solutions are mixed.
Predicting Solubility A Rule Summary Gen. Chem 1. Salts containing Group I elements are soluble. Ammonium (NH 4+) salts are also soluble. 2. Salts containing nitrate ion (NO 3 -) are generally soluble. 3. Salts containing Cl -, Br -, I - are generally soluble. 4. Most sulfate salts are soluble. 5. Most hydroxide salts are only slightly soluble. Hydroxide salts of Group I elements are soluble. Hydroxide salts of Group II elements (Mg, Ca, Sr, and Ba) are slightly soluble. Hydroxide salts of transition metals are insoluble. 6. Most sulfides of transition metals are highly insoluble. 7. Carbonates are frequently insoluble. 8. Phosphates are frequently insoluble.
Making a Salt, Quantitatively Gen. Chem Arsenic (III) sulfide (As 2 S 3) is a paint pigment known as orpiment. It is believed to have been first used more than five thousand years ago. It is an insoluble salt that can be made by mixing a solution of arsenic (III) nitrate with a solution of sodium sulfide. Consider a painter who requires exactly 0. 100 g of arsenic (III) sulfide. How much 0. 100 M arsenic(III) nitrate and how much 0. 100 M sodium sulfide will the painter need to mix together to get exactly 0. 100 g?
Gen. Chem Following the logic train 0. 100 g of arsenic (III) sulfide from 0. 100 M arsenic(III) nitrate and 0. 100 M sodium sulfide. How much of each? Ø Create formula: Ø Determine molar mass Ø Determine moles arsenic(III) sulfide required. Ø Determine moles arsenic (III) and sulfide required. Ø Determine volume of solutions required to deliver that amount.
Gen. Chem Charging for hints This is a timed test and there a number of places where you could possibly get “stuck”. To prevent catastrophic failure, should you get stuck you will be sold information to allow you to proceed. The cost will vary but will not total more than 10% of the practical score. Knowledge that can be purchased • Formula of your salt. • Molar mass of your salt. • Equation formation of your salt.
Let′s explore! Gen. Chem Your First Challenge Class project: Determine which salt is your assigned color. Available resources: You have only 15 minutes v Solutions of the seven salts; to figure this out. v well plate.
Let′s explore! Gen. Chem Your Next Challenge Figure the volumes of solutions that need to be mixed to produce your 0. 250 grams of pigment. You have only 15 minutes to figure this out. If you don’t have an answer in 15 minutes you’ll have to buy one.
Gen. Chem Pointers for preparing your pigment. 1. The precipitate will filter better if you let it “age” first. A minimum of 10 minutes is recommended. 2. When drying your product using the hot plate make sure the setting is not greater than 5. Watch for charring. Move the filter paper around if it begins to char. 3. Time will be an issue for many. There a couple of places in the procedure where you need to wait. This would be a good time to begin constructing your report. 4. You will need a percent yield to successfully complete your report.
Let′s explore! Gen. Chem Your personal Challenge Design and carry out a procedure for preparing exactly 0. 250 gram of your pigment. Available resources: v solutions of the seven salts; v 25 -m. L graduated cylinder; v 100 -m. L beakers v funnel and filter paper. v balance You have 45 minutes. As this is a test, you are now on your own. No more group work.
The Report You will now write your report for this experiment. Gen. Chem Report Content: v Abstract. Brief description of the report’s content. v Introduction. Background information necessary to understand the experiment. v Raw data. A copy of all measurements and observations you collected in lab. v Results. An organized presentation of the results obtained. v Calculations. Examples of the various calculations performed. v Discussion. A discussion of the results obtained, their credibility and their meaning.
Your Final challenge! Gen. Chem Your Discussion should address • The identity of your selected pigment including the formula. • The chemical equation for the manufacture of the pigment. • An outline of the recommended procedure for preparing 1. 0 kg batches of the pigment including your justifications for the amounts of materials required. • Your projection of manufacturing problems that may occur based on your observations and understanding of the properties of the materials involved