Properties of Water Lab: Water and solutions Background: Water has several unique properties. The hydrogen bonding that occurs between molecules in water results in much higher melting and boiling points as well as much lower vapor pressure; this allows the water to exist at temperatures that make life on our planet possible. In this lab we will use a variety of common household items and substances to explore the unusual properties of water. Purpose: To investigate the unique properties of water. Procedure: Students will work in table groups and rotate through the lab stations to explore different properties of water. Each student will complete the lab and answer question in their lab notebook. No formal lab is required for this activity. TURN-IN: a. Complete lab in the notebook. b. Make sure you have your name and period on the front cover. c. Turn in the notebook at the end of class. Assessment: Not Proficient Work Ethic: Any of the following: ● Missing elements listed in proficient ● JEOPARDIZES SAFETY. ● Work is late Proficient Exceeds Proficiency Includes most of the following: ● Student is on task and works consistently to complete lab during class period ● Student leaves lab area clean and prepared for next class ● Work is completed on time Includes most of the following: ● Student helps to clean common areas OR ● Student assists other students when appropriate OR ● Student attempts to find solutions to problems or questions independently, with group members, or research Teamwork: Missing elements listed in proficient. Includes most of the following: ● Works with group members by remaining positive ● Does not distract others ● Positively contributes to the group’s lab completion Includes most of the following: ● Student assists other group members as necessary Communication: Missing elements listed in proficient. Includes most of the following: ● Answers fully address question ● Limited grammatical errors and conventions ● Uses scientific language (avoid the use of pronouns like I, you, me, we, our, etc.) and is concise but detailed Includes most of the following: ● Discussion fully connects findings or implications to class concepts or real world events with at least one external citation.. ● Appropriate scientific vocabulary used extensively and accurately Lab Station 1: Drowning Lincoln 1. Split your group in half so each person has a partner. 2. Obtain two pennies, two pipettes, and a beaker with 200ml of tap water. 3. One person from each pair will, using the pipette, count the number of drops of tap water that can place on the head of your penny before the water spills over the side. 4. Perform two additional trials by repeating steps 1 and 2. Record the number of drops in the data table. 5. Repeat steps 1 and 2 using the detergent solution. Record this number in the data table. 6. Perform two additional trials by repeating step 5 twice. 7. Clean lab station for next group. # of Drops Tap Water Detergent Solution Observations Trail 1 Trial 2 8. Record observations for both tap water and detergent solutions. 9. What specific characteristics of water are at work at this lab station? Lab station 2: Floating a Paper Clip 1. Obtain a paper cup and a paper clip. 2. Fill the paper cup to the edge with tap water. 3. Carefully slid the paper clip onto the surface of the water. Record your observations. 4. Remove the paperclip and add approximately ½ teaspoon of salt to the water in the paper cup. 5. Repeat step three using the salt solution. Record your observations here: 6. Clean up lab station for next group. 7. What specific characteristics of water are at work at this lab station? Lab Station 3: Dispersion of Oil 1. Obtain a Petri dish, a rubber band, a small amount of vegetable oil, and liquid dish detergent. 2. Thoroughly clean and dry the Petri dish. 3. Fill the Petri dish almost all the way full of water. 4. Carefully place the rubber band on the surface of the water. 5. Slowly add oil drop wise to the water inside the rubber band until it is covered by a layer of oil. Record your observations here. 6. Add one drop of liquid detergent to the center of the oil layer. Record your observations. 1. Clean up the lab station for the next group. 2. What specific characteristics of water are at work at this lab station? Lab Station 4: Layers of Liquids 1. Obtain corn syrup, green isopropyl alcohol, Kool-aid, vegetable oil, and a 100ml graduated cylinder. 2. Pour 10ml of corn syrup into the graduated cylinder. 3. Slowly add 10ml of kool-aid to the graduated cylinder by pouring it down the side. 4. Slowly add 10ml of vegetable oil to the cylinder by tipping it and pouring it down the side. 5. Very carefully add 10ml of rubbing alcohol on top of the oil. Record your observations 1. Cover the mouth of the graduated cylinder with the palm of your hand and carefully shake it up and down. Allow the cylinder to sit for at least 1 minute. Record your observations 1. Pour the contents of the graduated cylinder down the sink; wash the cylinder with dish soap using a test tube brush. Clean the lab station for the next group. 2. What specific characteristics of water are at work at this lab station? Lab Station 5: Test pH 1. Dip the tip of a strip of pH indicator paper into each test tube and leave for at least 15 seconds. 2. Use the color scale on the indicator package to estimate the pH of each solution. 3. Use a different strip of pH indicator for each solution. 4. Record results in the table below. 5. Label the pH scale below with the solutions. Ph of Common Household Substances Solution pH Acid or Base? 7-UP Dr. Pepper Energy Drink Water Window Cleaner Mouthwash Questions (You may need to also refer to notes or the text): 1. What is the overall charge on a molecule of water? 2. The polarity of water was demonstrated in which lab station? Explain why this is so. 3. Explain what occurs when several water molecules are near each other in a droplet. 4. Is water the only molecule that is polar? Why or Why not? 5. What is the property of water molecules being attracted to other water molecules called? 6. Explain what causes water to have surface tension and give an example of how to prove this through a laboratory experiment.
