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Investigatory

Crazy Crystal Creations: How to Grow the Best and the Largest Crystals Materials and Equipment * Lab notebook * Large bowl * Ice, enough to fill large bowl at least three times * Water * Thermometer * String * Scissors * Pencils (3) * Identical jars or large drinking glasses (3) * Pot with a lid * Borax (also called 20-Mule Team household cleaner); * Tablespoon * Plastic wrap, wax paper, or aluminum foil * Gloves, latex or similar style exam glove (optional). Can be used if there is concern over handling borax Experimental Procedure 1.

In this science fair project, you’ll be recrystallizing borax under three different temperature conditions: in a refrigerator, at room temperature, and in an ice bath.

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Before you begin, make a hypothesis, based on your background reading, about how the crystals grown under each of these conditions will look. Write your hypothesis in your lab notebook. 2. Prepare an ice bath by filling the large bowl half full of ice and then adding water until the bowl is three-quarters full. a. Place the ice bath on a counter top or on a table, where it can be left undisturbed for at least 5 hours while the crystals grow. . As soon as the ice bath is prepared, use the thermometer to take the temperature of the ice bath, of the refrigerator, and of the room (do this by putting the thermometer on the countertop or table), and record the temperatures in your lab notebook. 4. Cut three pieces of string and tie one around each pencil. The string pieces should be of equal length and should be long enough that when the pencil is laid across the top of the jar, the end of the string hangs down to just above the bottom of the jar. 5.

Bring enough water to fill each jar three-fourths full to a boil in a pot, with adult supervision. 6. Add 1 tablespoon (Tbsp. ) of borax to the water, and stir until it dissolves. Repeat, 1 Tbsp. at a time, until no more borax will dissolve. This is your saturated solution. 7. With an adult’s help, pour equal amounts of the saturated solution into the three jars. The jars should be about three-fourths full. 8. Lay a pencil across the top of each jar so the strings hang down into the saturated solution. 9. Cover the jars with plastic wrap, wax paper, or aluminum foil. 10.

Place one jar in the refrigerator, leave one undisturbed on a countertop or table at room temperature, and put one in the ice bath you prepared. 11. Leave the jars alone for a minimum of 5 hours, or until crystals form (whichever is longer), and be sure not to disturb them. Check the ice bath regularly to make sure that the ice has not melted. Add ice, as necessary. b. If crystals form under one condition before they do in the others, note that in your lab notebook and let all three conditions continue for another hour to see if any crystals form in the other conditions. . Record in your lab notebook the total amount of time (from step 9 to step 11) that you let the crystals form. 12. Carefully remove the pencils, one at a time, and note the size, shape, and number of crystals obtained from each solution. Are there any differences? Why do you think this is so? Record your observations in a data table, like the one below. Cooling Condition| Trial 1| | Temperature| Time of Crystal Formation (in hours)| Number| Size| Other Observations| Ice bath|  |  |  |  |  |

Refrigerator|  |  |  |  |  | Room temperature|  |  |  |  |  | 13. If you are presenting your project in a science fair, save the strings and display them at the fair. Be sure to keep track of which string belongs with which solution. 14. Repeat steps 1–13 at least two more times to make sure that your results are accurate and repeatable. How do your results compare to your hypothesis? What Makes Ice Melt Fastest? Materials and Equipment To do this experiment you will need the following materials and equipment: Ice cubes * Identical plates or saucers * Timer * Electronic kitchen balance (accurate to 0. 1 g) * Measuring cup * Suggested materials to test for ice-melting ability * Table salt * Sugar * Sand * Pepper Experimental Procedure 1. Do your background research so that you are knowledgeable about the terms, concepts, and questions, above. 2. You’ll need a clean plate and several ice cubes for each of the substances to be tested. 3. Use the balance to measure the initial mass of the ice cube.

Note the starting time, then carefully sprinkle one teaspoon of the substance to be tested over the ice cube. 4. After a fixed amount of time (say, 10 minutes), pour off the melted water into a measuring cup, and use the balance to measure the mass. Subtract the mass of the empty cup, and you’ll have the mass of the melted water. Wait the same amount of time for each test. 5. Measure the remaining mass of the ice cube. 6. Repeat three times for each substance to be tested. 7. Use the same procedure to measure the melting rate for ice cubes with nothing added. 8.

For each test, calculate the percentage of the ice cube that melted: [mass of melt water]/[initial mass of ice cube] ? 100 9. For each test, calculate the percentage of the ice cube remaining: [remaining mass of ice cube]/[initial mass of ice cube] ? 100 10. For each substance you tested, calculate the average amount of melted water produced (as a percentage of initial mass), and the average remaining ice cube mass (as a percentage of initial mass). 11. Did any substances speed up melting of the ice (compared to melting rate of plain ice cubes with nothing added)?