TASK 1: EVAPORATION of SALT WATER
Part A: Hypothesis and Data Collection
What do you think will happen when you leave the paper in the container overnight?
Your response: I think the water will evaporate from the paper, leaving salt residues behind. The paper will likely be dry to the touch by morning.
Now leave the paper in the container overnight. In the morning, look at the paper and write down your observations.
Your response: In the morning, the paper was dry, and I noticed some white salt crystals on the surface. The paper also had a slightly different texture from before.
Evaporation happens in the ocean as part of the water cycle. What fuels evaporation in the ocean?
Your response: The Sun provides the necessary heat energy to fuel evaporation in the ocean, warming the water and causing it to change from liquid to gas.
Some ocean water evaporates, but certainly not all of it. When evaporation occurs, what happens to the ocean water that doesn’t evaporate? Explain in terms of the salt content and what you saw in the experiment.
Your response: The ocean water that doesn’t evaporate becomes saltier because the salt remains in the water while the freshwater evaporates. This is similar to the salt remaining on the paper after the water evaporated during my experiment.
Part B: Analyze and Extend
Were your predictions correct? Explain using complete sentences.
Your response: Yes, my predictions were correct. The paper did dry out, and I observed salt crystals left behind just as I expected. This demonstrated how evaporation removes water but leaves the dissolved substances, like salt, behind.
What process caused the changes that occurred on the paper?
Your response: The process that caused these changes is evaporation, where water transitioned from liquid to vapor, leaving the salt to crystallize on the paper.
TASK 2: SALINITY of WATER and DENSITY
Part A: Hypothesis and Data Collection
What do you think will happen when you mix the salt water with the water in the plastic container?
Your response: I think the saltwater will either sink or stay at the bottom because it is denser than freshwater, creating a separation between the two layers.
Now, slowly pour the salt water into the plastic container with the tap water. Write down your observations.
Your response: When I poured the saltwater into the plastic container, I noticed that the saltwater created a distinct layer at the bottom and did not mix completely with the freshwater. The saltwater appeared darker due to the food coloring.
Part B: Analyze and Extend
Did your observations match your predictions when you mixed the water?
Your response: Yes, my observations matched my predictions. The saltwater remained as a separate layer on the bottom instead of mixing evenly with the freshwater.
What caused the change that you saw in the water mixture?
Your response: The change was caused by the difference in density between the saltwater and freshwater. The denser saltwater sank to the bottom instead of mixing with the less dense freshwater.
Density:
- Your response: Increased density due to the added salt.
Mass:
- Your response: The mass increased because I added salt to the water.
Volume:
- Your response: The volume increased because I added more saltwater to the container.
If you repeated the experiment with a glass of water that had 5 teaspoons of salt and another glass that had 10 teaspoons, what do you think would happen?
Your response: The glass with more salt (10 teaspoons) would likely be denser than the glass with 5 teaspoons, affecting how the two mixtures interact when combined.
Compare this experiment to the evaporation of salt water in the ocean. Think about what happens when ocean water evaporates. How would that affect the salinity and density of the ocean?
Your response: When ocean water evaporates, the remaining water becomes saltier and denser, similar to what I observed in the experiment when the saltwater did not mix with freshwater. This increased density affects ocean currents and ecosystems.
TASK 3: BUILDING a MODEL of OCEAN CURRENTS
Hypothesis and Data Collection
Make a prediction. What do you think will happen when you add the hot and cold water to the water in the clear container?
Your response: I predict that the hot water will rise to the top because it is less dense, while the cold water will sink to the bottom due to its higher density.
Hold one cup in each hand and gradually pour the hot water into one end of the container and the cold water into the other end. Be sure you pour both at the same time, slowly. Watch the water for one minute and record your observations.
Your response: I observed that the hot water rose and spread out at the top, while the cold water sank and created a distinct layer at the bottom. The two colors swirled somewhat but did not mix completely.
The temperature of the ocean is different at the surface than it is near the deep ocean floor. Why do you think that is the case?
Your response: The surface water is heated by the Sun, while the deeper water is insulated from the heat. Additionally, cold water tends to sink, leading to a temperature gradient in the ocean layers.
Based on your results from task 2, do you think that cold ocean water tends to be saltier or less salty than warm ocean water? Think about density. Explain using complete sentences.
Your response: Cold ocean water tends to be saltier than warm ocean water. This is because as warm water evaporates, it leaves behind salt, increasing the salinity and density of the cooler water below.
Sometimes the flow of ocean currents is compared to the movement of a conveyor belt. Does your experiment support this statement? Explain using complete sentences.
Your response: Yes, my experiment supports this statement. I observed that the hot water (representing surface currents) moved to the top while the cold water (representing deep currents) moved downward. This shows how warmer, less dense water can rise, creating a cycle similar to a conveyor belt.
The Sun hits the ocean at the equator more directly than at the poles. How does this affect the flow of currents in the ocean? Explain using complete sentences.
Your response: The direct sunlight at the equator heats the water more than at the poles, causing the warmer water to expand and rise. This creates a flow of warmer water toward the poles and contributes to ocean currents by driving the movement of both warm and cold water, influencing global climate patterns.
Dispose of your waste properly: Pour the water from the glasses and containers down the drain.