Salt Level Demonstration

Part of the Ecology Disrupted Curriculum Collection.

A salt shaker on a surface next to four measuring spoons.

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Salt Level Demonstration teacher's guide

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TEACHER'S GUIDE

What appears to be very little salt can cause big environmental changes like changing freshwater to saltwater.

Materials

  • Water
  • Salt
  • Graduated cylinder
  • Digital scale, if available; or measuring cup and spoons

Demonstration

Key Idea: What appears to be very little salt can cause big environmental changes like changing freshwater to saltwater.

Use a 1000 ml graduated cylinder and a digital gram scale if available to measure out: 

  1. 1 mg table salt and 1000 ml of water = Salt levels of 1mg/L (freshwater)
  2. 250 mg table salt and 1000 ml of water = Salt levels of 250 mg/L (EPA drinking water guidelines; freshwater)
  3. 1 gram table salt and 1000 ml of water = Salt levels of 1000 mg/L (considered slightly salty; brackish water)
  4. 3 grams table salt and 1000 ml of water = Salt levels of 3000 mg/L (NY/NJ Harbor Estuary water, considered moderately salty; estuary water that changes with the tides)
  5. 10 grams table salt and 1000 ml of water = Salt levels of 10,000 mg/L (NY/NJ Harbor Estuary water considered very salty) 
  6. 35 grams table salt and 1000 ml of water = Salt Levels of 35,000 mg/L (Very salty; open ocean water) 

Teacher Tip

Use teaspoons and a measuring cup to measure out the same quantities, so that students can taste the differences in salt:

  1. A. 1mg/L ~ 0 tsp. of salt in 4 ¼ cups of water
  2. B. 250 mg/L ~ 1/19 tsp. salt in 4 ¼ measuring cups of water
  3. C. 1000 mg/L ~ 1/4 tsp. salt in 4 ¼measuring cups of water
  4. D. 3000 mg/L ~ 5/8 tsp. salt in 4 ¼ measuring cups of water
  5. E. 10,000 mg/L ~ 2 and 1/8 tsp. salt in 4 ¼ measuring cups of water
  6. F. 35,0000 mg/L ~ 7 and 1/3 tsp. salt in 4 ¼ measuring cups of water