Name and Section: _____________________

Miss Rose, Putnam Ave Upper School, Cambridge 1

Rock Candy Lab Series Boiling Point, Crystallization, and Saturation

You will do a series of short, “mini-labs” that will lead up to a lab in which you make your very own rock candy. The Rock Candy Lab will count as a project, 40% of your grade, while the mini-labs will count as separate participation grades (each worth 15% of your grade). Bring this sheet with you to class every day while we complete these labs. Each one will help you gain new knowledge that you will later apply to the rock candy project. You may work with ONE other person from your table. We will start the labs together as a class, but you and your partner may work at your own pace. Everyone at your table will share materials. tobear Please make sure you clean up after yourself after each lab! Mini-Labs Check List:

1. Boiling Points: Do different amounts of water have different boiling points? Can we add something to water to change its boiling point?

2. Dissolving: Does sugar dissolve differently in different liquids?

3. Solubility Tests: Compare how different substances crystallize.

4. Saturation: See how much sugar will dissolve in cold water, then in hot.

Rock Candy Lab Project: Miss Rose will give you a separate set of instructions once you have successfully completed these four mini-labs.

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1. Boiling Points

1. Pre-Lab: Will the temperature at which water boils change depending on the amount of

water being boiled? Why or why not? Write your thoughts down here: 2. Pre-Lab: How would you design an experiment to test this? (available materials: water, beakers,

thermometers, hot plate, and you may request anything else we have in the lab). 3. Lab: Conduct the experiment you designed and write down any data here. Include a table and/or

sketches: 4. Post-Lab: Will the temperature at which water boils change depending on the amount of

water being boiled? Why or why not? Write down your answer to this question after you have collected some data: 5. Post Lab: If you add sugar or salt to the water, does it change its boiling point? Give data in

your answer.

Use the back of this sheet if you need extra writing space.

Name and Section: _____________________

Miss Rose, Putnam Ave Upper School, Cambridge 3

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2. Dissolving

Name and Section: _____________________

Miss Rose, Putnam Ave Upper School, Cambridge 5

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3. Solubility Tests/Crystallization

Can you identify the unknown crystal by how it dissolves in water? Materials:

Triple beam balance Small piece of paper 5 Crystals: food salt, Epsom salt, MSG, sugar, and “unknown” 6 small cups 5 clear plastic cups plastic spoon hot water

First: Set up equal amounts of the crystals whose solubility you are going to examine. Use the triple beam balance to weigh out 4-5 grams of each on a piece of paper. Place each quantity into a small cup and label the cup with the crystal’s name. Pre-lab Questions:

1. What does it mean to conduct a controlled experiment?

2. If you are going to compare the solubility of each crystal, what other factors do you think should remain constant, or controlled?

Name and Section: _____________________

Miss Rose, Putnam Ave Upper School, Cambridge 7

Solubility Tests (Continued)

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Name and Section: _____________________

Miss Rose, Putnam Ave Upper School, Cambridge 9

4. Saturation

What is saturation, and does temperature have anything to do with it?

A solution in chemistry is a mixture of two or more substances. It is what is formed when one substance dissolves into another. For example, when you dissolve sugar in water, a sugar-water solution is formed. To get even more technical, the sugar in this instance is called the solute and the water is called the solvent. When a liquid (or solvent) has dissolved as much of the solute as it can possibly hold, we say it is saturated. In this lab, you will examine the effects of temperature on saturation of sugar in water. Saturation is important in candy-making, as you will later find out.

1. Pre-Lab: Vocab: Define the following:

a. dissolve:

b. solute:

c. solvent:

d. saturated:

e. super saturated:

2. Pre-Lab: Do you think the temperature of the water will have anything to do with how much sugar will dissolve in it? Explain your guess.

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3. Pre-Lab: How would you design an experiment to test your guess? (Available Materials: measuring spoons, water, hot plate, sugar, thermometer, tin foil cups, tongs, and anything else in the lab). Discuss your plan. What factors will you vary? What will you keep constant? Why? Include sketches or diagrams, and note the kinds of data you will write down.

4. Lab: Carry out the steps in your plan. Take any notes and data here:

5. Post Lab Questions: f. What happened when you tried to dissolve sugar in cold water?

g. What happened when you tried to dissolve it in warm water?

h. Does temperature have an effect on saturation? Explain.

i. How could you tell when the solution was saturated?

j. Bonus: Does adding sugar to water change the water’s boiling point?