Monday, November 30, 2020

Saltwater to Salt and Water

 Planet Earth has been called a Water World. Seventy-one percent of Earth’s surface is covered by oceans. These are saltwater oceans making up about 97% of all water on Earth. The average depth of the ocean is almost 2 1/2 miles. Only 3% of Earth’s water is fresh (non-salty) water. Ocean water contains about 3.5% salinity. One liter of ocean water weighs 33.81 ounces of which 1.2 ounces is dissolved salt. This is how we calculate 3.5% salinity. Dissolved salt in one cubic mile of seawater amounts to an incredible 120 million tons. That amounts to 500 feet of salt piled upon each square foot of Planet Earth if all its water were to evaporate—enough to almost cover the Washington Monument!

Scripture contains many references and spiritual object lessons involving salt and water. Contemporary knowledge supplies an expanded scientific foundation for many biblical references to those substances. Both salt and water are necessary for life on Planet Earth. The most common aqueous solution on Earth is saltwater in our oceans, home to millions of different species of life. Almost 250,000 known species live in the ocean along with many more undiscovered species. Most ocean-dwelling species survive solely in salt water. A few are able to adapt to fresh water for portions of their lives. Therefore, it is appropriate to connect ocean saltwater with a substantial portion of life on our planet.

Our discussion relates to three substances—saltwater, salt, and water. The interrelationship of the three substances puts metaphorical “meat on the bones” of many science unit lessons from elementary school to graduate school.

Saltwater oceans cover 71% of Earth’s surface. There are 332.5 million cubic miles of liquid water on Earth of which 321 million cubic miles consists of saline water. Only 3% of Earth’s water is fresh water located in ice caps, glaciers, groundwater, swamps, lakes, and rivers. Potable fresh water is but a tiny fraction of the world’s supply of fresh water.

Humanity discovered long ago that pure salt and pure water are essential for human thriving. In modern times, we have discovered the processes of separating salty ocean water into safe, potable water and useful pure salt. Both water and salt are compounds—chemical combinations of two or more atoms forming a compound. Ocean water is the most common chemical solution of two compounds on the planet. From it we may derive pure salt and pure water.

Our last post briefly mentioned the process of salt production on the island of Bonaire in the Caribbean. ( We introduce a few terms to trigger your memory of former science classes: If a solute (salt in this case) dissolves in a solvent (water in this example) we obtain a solution, a homogeneous mixture of salt in water. Chemically, mixtures are reasonably easy to separate if you apply the correct method. Heating the salt water to its boiling point evaporates the water quickly. The water becomes increasingly concentrated with salt as the water boils away. Eventually the solution becomes saturated with salt. Further boiling causes the salt to precipitate—crystallize into its solid state. Eventually the water evaporates completely and only pure salt is left behind. On Bonaire the warm trade winds naturally evaporate the water in shallow salt water pools over several months. A harvest of salt is soon in prospect. Evaporated water, in a sense, is a waste product.

With respect to separating pure water from ocean saltwater, there are several technologies to accomplish the task. They include thermal distillation by boiling away the water and condensing the vapors to a liquid by cooling. “Reverse osmosis” may provide the best explanation for an ever-present modern problem faced by many countries involving their need for fresh water. We leave the explanation of the reverse osmosis process for a future post.

The Island of Bonaire currently supplies its residents with fresh water primarily with technology which utilizes “reverse osmosis.” This technology is currently used by many countries. In particular, the nation of Israel is becoming a source of water, not only for itself, but also for some surrounding nations. Water may be more vital than oil in many Mideast nations. Israel currently derives 55% of its water from desalination technology.

Availability of salt? Availability of pure water? Our God has supplied a virtually unlimited supply of both compounds—an example of the provision of our infinitely generous Creator.