Investigating Salinity
Recommended for grades 9–12.
Introduction
Salinity is a measurement of the saltiness or concentration of salt in water. Ocean water contains many different salts, but the most abundant is sodium chloride, also know as table salt. Sodium chloride accounts for about 86% of all the ions present in ocean water. Other salts that can be found in ocean water at significant levels are calcium chloride and magnesium chloride.
While the average salinity of ocean water is 35 ppt (parts per thousand) of salt dissolved in water, there are several factors that can increase or decrease its salinity. At the polar regions, freezing of ocean water increases the salinity of the surrounding water. Evaporation in hot, arid regions also increases the salinity. The Dead Sea, located in Israel, has salinity nearly seven times that of most ocean water. At the ocean’s surface, rain, snow, and melting ice are all responsible for decreasing the salinity. As rivers enter the ocean, they carry large volumes of fresh water into the ocean, causing salinity to decrease.
Objectives
In the Preliminary Activity, you will gain experience using a Conductivity Probe while determining the salinity of a saltwater sample provided by your teacher.
After completing the Preliminary Activity, you will first use reference sources to find out more about salinity before you choose and investigate a researchable question dealing with that subject.
Sensors and Equipment
This investigation requires each of the following Vernier sensors and equipment (unless otherwise noted):
Additional Requirements
You may also need an interface and software for data collection. What do I need for data collection?
Download Experiment Preview
The student-version preview includes:
- Step-by-step instructions for the Preliminary Activity
- List of materials and equipment
Note: The experiment preview of the Preliminary Activity does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.
Standards Correlations
See all standards correlations for Investigating Environmental Science through Inquiry »
Experiment 7 from Investigating Environmental Science through Inquiry Lab Book
Included in the Lab Book
Vernier lab books include a CD with word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.