Rock+Candy+Crystals

= Does changing the amount of seed crystal (sugar) affect how fast rock-candy crystals grow? =

By Renee and Isabella = __Task 1: Answer these Questions__ = __1.What is a solution?__ Normally a solution is an answer to a problem, but in science its is a mixture of a solid and a liquid where the solid dissolves into the liquid

__2. How do you make a saturated solution - what is a saturated solution?__ When you are adding a solid (like salt) to a liquid (like water) it will dissolve. If you keep on adding salt it gets to a point where you add too much and no more can dissolve. This is called a saturated solution.



__2. Which holds more sugar: cold water or hot water?__ Hot water can hold more solid (eg sugar or salt) before it becomes a saturated solution.

__3. How do crystals grow?__ Crystals grow through a process called nucleation. The sugar or salt molecules which are dissolved in the solution are attracted to each other almost like a magnet. They will clump together and start to form a crystal shaped solid.

__4. What is nucleation?__ Nucleation is a physical reaction. Its when the molecules in a saturated solution find a solid surface like a piece of string or some dust and start to form crystals around it.

__Task 2: List your independent, dependent and controlled variables:__
__1. Independent variable:__ The amount of sugar we put in. __2. Dependent variable:__ The size of the rock candy. __3. Controlled variables:__ = __Task 3: What is the hypothesis for your experiment?__ = That if the string is longer then we will get more crystals in less time. = __Task 4: What equipment do you need for your experiment?__ = = __Task 5: List all steps in the method of your experiment (try and include a diagram or video that helps explain):__ = Day 1
 * The jar size
 * The length of the string
 * The amount of liquid in each jar
 * The size of the weights (screws) used
 * Wool (about 45cm)
 * Water
 * Cup
 * Tablespoon measuring spoon
 * white sugar (3 cups)
 * Wax paper
 * Screws to use as weights (2)
 * pencils (2)
 * Glass jars, identical in size and shape (2)
 * Pot
 * Stove
 * Measuring cup (for liquid ingredients)
 * Measuring cup (for dry ingredients)
 * mixing spoon
 * Pot holders
 * Paper towel

1. Cut two pieces of wool. Each piece should be around 3cm longer than the height of the glass jars. 2. Set one of the pieces of string aside and do nothing to it. Soak the other piece of string in a cup of water for 5 minutes. 3. After soaking, use your hand to squeeze the extra water from the string. Roll the string in 1 tablespoon of sugar on a plate. The string will be coated with sugar. These small bits of sugar are the seeds on which other sugar crystals might grow. 4. Lay both your seeded (sugar-coated) string and your non-seeded string on a piece of wax paper overnight. Make sure they are not touching.

Day 2

1. Take the seeded string and tie one end to a screw that will be its weight. It is ok if some of the sugar falls off. Repeat with the non-seeded string and a second weight. Use the same type of weight for each string.

2. Tie the other end of each piece of string to a pencil. 3. Mark the edges of the pencil that is holding the seeded string so we know later which piece of string had sugar on it. 4. Put the seeded string into a jar and put the pencil across the mouth of the jar. Roll the pencil to wind the string until the weight is about 1cm from the bottom of the jar. Repeat for the non-seeded string, then take the pencils and strings out of the jars and set them aside. 5. Preheat the glass jars. If you put the hot sugar-water solution in a cold jar, it would be too big a temperature change which could make small crystals form along the glass. The small crystals might disrupt the rock candy formations. 6. Boil enough water to fill both jars. When the water is boiling, carefully pour it into the jars. 7. Leave the glasses sitting full of hot water until the sugar-water solution is ready.

__Make the sugar-water solution__

1. Add 1 cup of water to a pot. Once the water is boiling turn the heat down to low. 2. Add 2 cups of sugar to the hot water. 3. Mix with a mixing spoon until all the sugar has dissolved. 4. Turn the heat back up and wait until the sugar-water solution starts boiling again. Keep stirring so that the temperature is the same the whole way through the solution. 5. Remove the boiling sugar-water solution from the stove. 6. Keep adding sugar 1 tablespoon at a time. After adding each spoonful, make sure that the sugar is completely dissolved before adding another spoonful. 7. Keep adding sugar until no more will dissolve in the solution. Keep stirring and if even after a full 2 minutes of stirring, there is undissolved sugar at the bottom of your pot, return the pot to the stove. Heat the solution until it just begins to boil, then remove it from the stove. This will help get that last bit of sugar into the solution. 4. When the last bit of sugar has been dissolved, let the solution to cool for 5 minutes. 5. Tip the hot water out of the preheated glass jars. 6. After the sugar-water solution has cooled for 5 minutes, pour the solution into the two preheated glass jars, dividing the liquid equally between the two glasses. Be really careful when pouring the sugar-water solution; it is hot and will burn if spilled on your skin. 7. Move the jars of sugar-water solution to a place where they can be left undisturbed for one week. Place both jars in the same location. If the temperature changes too much it can muck up the crystallization process, so avoid putting the jars in places that get direct sunlight, or are near a heating or cooling vent. 8. Gently lower the weighted strings into the jars of sugar-water solution, one string per jar. media type="file" key="121_1993.mp4" width="300" height="300" 9. Tape the pencils holding the strings to the edges of the jars to stop the strings from being accidentally moved

10. Loosely cover the jars with a paper towel to prevent dust and debris from flying in, while still allowing evaporation to occur.

__Observations__

1. Make observations of your sugar-water solution jars for one week. On the seventh day, remove the strings from the jars and take measurements of your rock candy crystals. 2. If there is a layer of hardened sugar syrup coating the top of your jar, you can use a spoon to gently break that layer before pulling out your sugar crystals. 3. Briefly rinse the rock candy crystals in cold water, then leave them on a paper towel for 30 minutes to dry. 4. Using a ruler, measure the length of the rock candy, and the width at the widest point. Did seeding make a difference in the size of the rock candy that you grew?

__**Task 6: Observation and discussion**__

Days Spent in JarObservations Day 1 (the day the sugar-water solution was made) Day 2 (Saturday - weekend) Day 3 (Sunday - weekend) Day 4

Day 5 Day 6 Day 7 =__Task 7: Results__=


 * Days Spent in Jar || Observations ||
 * Day 1 (the day the sugar-water solution was made) ||  ||
 * Day 2 ||  ||
 * Day 3 ||  ||
 * Day 4 ||  ||
 * Day 5 ||  ||
 * Day 6 ||  ||
 * Day 7 ||

__Task 8: Conclusion__
Write a statement that says whether your hypothesis was wrong. If you were wrong, why were you wrong?