Water Hardness Study
Recommended for grades 5–8.
Introduction
When water passes through or over mineral deposits such as limestone, the levels of certain ions present in the water increase greatly and cause the water to be classified as hard water. This term results from the fact that calcium or magnesium ions in water combine with soap molecules. This forms a sticky scum that interferes with soap action and makes it “hard” to get suds. Soft water, such as rainwater or melted snow, is mostly free of these ions. Soft water, when mixed with soap will form suds. A Conductivity Probe can be used to test for ions in water. Hard water, because of the ions it contains, gives a high conductivity reading. Soft water gives a low conductivity reading.
In Part I of this experiment, you will learn how to test water hardness and find the hardness of the tap water in your school. In Part II, you will plan and do a water-hardness study.
Objectives
In this experiment, you will
- Use soap to find water hardness.
- Use a Conductivity Probe to find water hardness.
- Find the hardness of the water in your school.
- Apply what you learn as you do a water-hardness study.
Sensors and Equipment
This experiment 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 computer-based data collection
- List of materials and equipment
Note: The experiment preview of the computer edition 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 Middle School Science with Vernier »
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.