netw rks GeoLab Activity
NAME
DATE
CLASS
netw rks
GeoLab Activity The World
Water: Make It Fresh Enough to Drink Imagine people stranded on a life raft at sea. No matter how thirsty these people may become, they should never drink saltwater, even though it is all around them. If they drink the saltwater, they will find themselves becoming even thirstier. Instead, what these people might do is turn the saltwater into freshwater that is safe to drink. This process is called desalination. Desalination is nothing new. Greek and Roman soldiers did it thousands of years ago. Greek sailors obtained freshwater by boiling the saltwater. Roman soldiers used clay pots to trap the salt. Let’s take a look at how you can turn saltwater into freshwater by setting up a simple desalination system. Materials
• • • •
large glass bowl metric ruler tablespoon table salt
• • • •
short drinking glass plastic wrap string (optional) small rock
What to Do 1. Pour tap water into the bowl until it is about 2 inches (5 centimeters) deep. 2. Add two tablespoons of salt and stir until the salt has completely dissolved. 3. Place the glass upright in the water. The glass must be higher than the saltwater but shorter than the bowl. 4. Cover the bowl with plastic wrap. If necessary, use string to seal the bowl.
6. Place the bowl in direct sunlight. 7. Observe the bowl several times a day. 8. After 5 days, remove the plastic wrap and taste the water inside the glass. 1
Copyright by The McGraw-Hill Companies.
5. Place the small rock on top of the plastic wrap, centered over the glass inside the bowl.
NAME
GeoLab Activity
DATE
CLASS
netw rks
cont.
The World Lab Activity Report 1. Describing Describe the appearance of your desalination system after 24 hours and then each day after that. 24 hours
Day 2
Day 3
Day 4
Day 5
2. Contrasting How is the water in the bowl different from the water that collects in the glass?
Assessment Checklist Assess your GeoLab using the checklist below.
3. Drawing Conclusions Explain how evaporation and condensation turned saltwater into freshwater.
Followed directions and safety procedures Set up a simple desalination system as described Explained lab results in complete sentences Cleaned up work area
Take the Challenge
2
Copyright by The McGraw-Hill Companies.
The largest desalination plants in the world are located in the Middle East, where freshwater is scarce. Unlike your desalination system that depended on evaporation and condensation, some desalination plants in the Middle East depend on a process called reverse osmosis to turn saltwater into freshwater. Do some research and create a poster that illustrates how reverse osmosis works.
DATE
CLASS
netw rks
GeoLab Activity The World
Water: Make It Fresh Enough to Drink Imagine people stranded on a life raft at sea. No matter how thirsty these people may become, they should never drink saltwater, even though it is all around them. If they drink the saltwater, they will find themselves becoming even thirstier. Instead, what these people might do is turn the saltwater into freshwater that is safe to drink. This process is called desalination. Desalination is nothing new. Greek and Roman soldiers did it thousands of years ago. Greek sailors obtained freshwater by boiling the saltwater. Roman soldiers used clay pots to trap the salt. Let’s take a look at how you can turn saltwater into freshwater by setting up a simple desalination system. Materials
• • • •
large glass bowl metric ruler tablespoon table salt
• • • •
short drinking glass plastic wrap string (optional) small rock
What to Do 1. Pour tap water into the bowl until it is about 2 inches (5 centimeters) deep. 2. Add two tablespoons of salt and stir until the salt has completely dissolved. 3. Place the glass upright in the water. The glass must be higher than the saltwater but shorter than the bowl. 4. Cover the bowl with plastic wrap. If necessary, use string to seal the bowl.
6. Place the bowl in direct sunlight. 7. Observe the bowl several times a day. 8. After 5 days, remove the plastic wrap and taste the water inside the glass. 1
Copyright by The McGraw-Hill Companies.
5. Place the small rock on top of the plastic wrap, centered over the glass inside the bowl.
NAME
GeoLab Activity
DATE
CLASS
netw rks
cont.
The World Lab Activity Report 1. Describing Describe the appearance of your desalination system after 24 hours and then each day after that. 24 hours
Day 2
Day 3
Day 4
Day 5
2. Contrasting How is the water in the bowl different from the water that collects in the glass?
Assessment Checklist Assess your GeoLab using the checklist below.
3. Drawing Conclusions Explain how evaporation and condensation turned saltwater into freshwater.
Followed directions and safety procedures Set up a simple desalination system as described Explained lab results in complete sentences Cleaned up work area
Take the Challenge
2
Copyright by The McGraw-Hill Companies.
The largest desalination plants in the world are located in the Middle East, where freshwater is scarce. Unlike your desalination system that depended on evaporation and condensation, some desalination plants in the Middle East depend on a process called reverse osmosis to turn saltwater into freshwater. Do some research and create a poster that illustrates how reverse osmosis works.
