Properties of Water Lab ______ / 65 = _______% Name: Date: Introduction: Water is essential to life. It is one of the simplest yet most important molecules in the natural world. Our bodies are made up of about 60% water. As you complete this lab, you will be investigating the properties of water. It is important to refer back to your notes on sections 2.1 and 2.2 during this lab. * It is important to make predictions for each station before you start the activity at that station. * Define the following terms using only your notes. (7pts) 1. Polarity (Polar Molecule): 2. Hydrogen Bond: 3. Adhesion: 4. Cohesion: 5. Surface Tension: 6. High Specific Heat: 7. Nonpolar Molecule: Draw a water molecule, labeling the positive end, the negative end, the oxygen, and the hydrogen atoms, and how it would connect to another water molecule. Label the bond it forms when it connects to another water molecule. (2pts) Drawing: Station One: Prediction: How many drops of water do you think will fit on the face of a penny? _________ drops (1pt) At this station you will be investigating how many drops of water can fit onto a penny. Place a penny flat onto a paper towel. Use an eyedropper to drop water one drop at a time onto the face of the penny. Count the number of drops as you add them. Stop counting and adding drops as soon as the water overflows. Record the number of drops in the data table. Repeat 2 more times for a total of three trials. Calculate an average for all three trials. (Data table: 4 pts) Trial # 1 # of drops Trial #2 # of drops Trial #3 # of drops Average # of drops 1. Using your notes and thinking back to our discussion in class, explain what properties of water are being demonstrated here. What property of water allows water to build up on the penny without rolling off? Answers should name the property(ies) of water and give a complete explanation. (2pts) 2. Apply this property to real life. How does life itself depend on this property of water? Hint: think about cells and how small they are, and what is in them. (2 pts) Station Two: Prediction: How will water behave when you drop it drop by drop on a piece of wax paper? (1 pt) ___________________________________________________________________________________________ How will oil behave when you drop it drop by drop on a piece of wax paper? (1 pt) __________________________________________________________________________________________ At this station, you will be investigating the behavior of water, which is polar, on wax, which is nonpolar. Using a glass eye dropper, drop several drops of water across several places on the wax paper. Place a toothpick in the middle of one of the drops, move the drop of water around the wax paper bumping it into the other drops of water on the paper. 1. Using your notes and thinking back to our discussion in class, explain what property of water is being demonstrated here. What property of water allows it to build up on the wax paper and form a big bubble on the wax paper? Answers should name the property of water and give a complete explanation. (2pts) Use the same procedure as above, except this time use oil (nonpolar). 1. What happened between the oil and the wax paper? Why do you think this occurred? (2pts) 2. How can you apply what happened in this simulation to real life? Use the terms dissolving, polar, and nonpolar in your answer. (2 pts) Station Three: Prediction: What will happen when you place a paper clip on the top layer of water in a filled beaker? (1) ___________________________________________________________________ What will happen to the paper clip if you drop a drop of dish soap into the beaker? (1) ___________________________________________________________________ Use a clean beaker (wipe it out with a paper towel after it has been rinsed). Fill the beaker all the way to the top (just before it is ready to spill over). Take a paper clip and gently release the paper clip onto the top of the water until it floats. 1. The density of a paper clip is greater than the density of water, so it should not float based on this idea alone. Explain what property of water allows the paper clip to float. (2) 2. How is this property of water important to real life? Think about a water spider or insects that walk on water. (2) 3. Place a few drops of dish soap into the beaker. Observe the paper clip. Explain what happened to the paper clip based on your knowledge of the property of water. (2) Station Four & Five (Demonstration by the teacher) Predictions: What will happen when ice is placed in a beaker filled with water? (1) __________________________________________________________ What will happen to ice when it is placed in a beaker of alcohol? (1) _________________________________________________________ What will happen when a hollow tube is placed in a petri dish filled with blood/water? (1) _________________________________________________________ Station Four (Teacher demo) Ice is added to a beaker of water, and then ice is added to a beaker of alcohol. 1. What happened when ice was added to water? Why did this occur? (Hint: think density and hydrogen bonds) (2) 2. What happened when ice was added to alcohol? Why did this occur? (Hint: think density and hydrogen bonds) (2) 3. How is what you witnessed in this station very important for aquatic life in the winter when lakes freeze? (2) 4. Apply the property of high specific heat to the lake scenario. (How is the water below the ice able to stay in liquid form) (2) Station Five (Teacher Demo) Place a hollow capillary tube into a petri dish filled with blood (colored water). 1. What happens to the blood/water mix when the tube is placed in it? (2) 2. What property of water is being shown here? (2) 3. How does life depend on this property of water? (think about blood in the body, and water moving from the ground 10 feet up to the leaves in a tree) (2) Additional Questions: (14pts) 1. When you make a pitcher of iced tea you add scoops of the sugar mix to a container of water. What property of water allows it to dissolve the sugar mix? 2. What would the water be considered in this solution? The sugar? 3. Because water is ___________________ it has the ability to form ________________________ bonds. 4. Because water can form ___________________ bonds it can stick to other water molecules giving it the property of ______________________. 5. Because water can form _______________________ bonds with other polar molecules, it has the property of _______________________. 6. Because water can form ______________________ bonds, it has the ability to resist extreme changes in temperature, this is known as the property of _______________________________________. 7. Suppose you had a high fever, how would water’s ability to resist changes in temperature (high specific heat) be important for the water in your body?