How does fresh water differ from ocean water?
Ocean water contains about 3.5% table salt (NaCl), while fresh water has a much lower concentration of salt (about 0.05%). Since the human body has a salt concentration of about 0.9%, drinking ocean water actually dehydrates or removes water from the cells of the body. Human body cells require water to complete a number of different cellular processes. Drinking fresh water provides these cells with water to carry out the necessary functions of the cell.
What percentage of the water on Earth is fresh water?
Over 75% of planet Earth is covered by water. However, about 97.5% of all of the water on Earth is ocean water, or water with a salt concentration of about 3.5%. In fact, only around 2.5% of Earth's water is fresh water for direct human consumption. While ocean water is highly abundant, fresh drinking water sources are much scarcer than sea water.
What percentage of Earth's fresh water is readily available in lakes, river, and streams?
Most of Earth's fresh water is not readily available for human consumption. About 70% of this water is locked up in ice caps and would have to first be melted before yielding drinking water. Other fresh water is in the atmosphere or deep within the earth in locations not reachable with current technologies. Only 1.3% of fresh water is located in regions where relatively easy access to the water is available.
What are some common methods for purifying ocean water?
Although currently costly, ocean water can be purified or desalinated for human drinking. A number of process can remove the salt from ocean water, including ion exchanges, reverse osmosis, and boiling or freezing the ocean water. Some have even suggested that icebergs could be lassoed, towed to dry regions, and melted to supply drinking water. A more practical solution is to use small temperature gradients between different depths of ocean water to power a desalination plant. All of these methods have limitations and generally are much more expensive than using existing fresh water supplies.
What are the characteristics of each phase of matter?
Matter can exist in different states. The three most common states of matter found here on Earth are solid, liquid, and gas. For instance, H2O exists as a solid, known as ice, a liquid, what we drink and call water, and as a gas, called water vapor. Each state of matter has distinct features. The following chart shows some of these features.
Here are some definitions to help you in your Grade 3-5 Lesson 1 investigation.
Drought - a lack of rainfall in a given area
Desalination - turning salt water from the ocean into fresh drinking water
Flash Chamber - a device that holds liquid, turns it into a gas, and holds the gas
Aerosolizer - a device that changes a liquid into much smaller and lighter particles that can be carried in the air
Condenser - a device that changes a gas into a liquid
Intake - where a substance enters a system
Outlet - where a substance exits a system
Return - where a substance is moved to its original location
Change of Phase - to go from one phase of matter to another phase of matter
Condensation - to move from the gas phase to the liquid phase
Vaporization - to move from the liquid phase to the gas phase
Liquid - a phases of matter where particles move less than in the gas phase
Gas - a phase of matter where particles have lots of motion
Temperature - a measure of the motion of a particle or the hotness or coldness of something
Here are some definitions to help you in your Grade 3-5 Lesson 2 investigation.
Desalination - turning salt water from the ocean into fresh drinking water
Flash Chamber - a device that holds liquid, turns it into a gas, and holds the gas
Aerosolizer - a device that changes a liquid into a gas
Condenser - a device that changes a gas into a liquid
Here are some definitions to help you in your Grade 3-5 Lesson 3 investigation.
Kinetic Energy - energy due to the motion of an object or particle
Temperature - a measure of the average kinetic energy of the particles of a substance
Temperature Difference - how far two temperatures are apart
Volume - the amount of space something fills
Liters - a measure of volume
Volume Flow Rate - the volume that moves past a given point in a given unit of time
Liters/hour (liters/hr) - a unit for measuring volume flow rate
"Water, water, everywhere, nor any drop to drink." This line from the famous poem, The Rime of the Ancient Mariner, describes the condition many have faced when surrounded by seawater and in dire need of a drink of water. Ocean water is about three times saltier than a human’s blood and therefore, cannot be used as a thirst quencher. People have invented a number of techniques for purifying ocean water. Do you think it’s economically possible to change ocean water into fresh drinking water? Take a splash into this lesson and find out.)
