Vernier Software and Technology
Vernier Software & Technology

pH

Figure from experiment 11 from Earth Science with Vernier

Introduction

Water contains both hydrogen ions, H+, and hydroxide ions, OH-. The relative concentrations of these two ions determine the pH value. Water with a pH of 7 has equal concentrations of these two ions and is considered to be a neutral solution. If a solution is acidic, the concentration of H+ ions exceeds that of the OH- ions. In a basic solution, the concentration of OH- ions exceeds that of the H+ ions. On a pH scale of 0 to 14, a value of 0 is the most acidic, and 14 the most basic. A change from pH 7 to pH 8 in a lake or stream represents a ten-fold increase in the OH- ion concentration.

Rainfall generally has a pH value between 5 and 6.5. It is acidic because of dissolved carbon dioxide and air pollutants, such as sulfur dioxide or nitrogen oxides. If the rainwater flows over soil containing hard-water minerals, its pH usually increases. Bicarbonate ions, HCO3-, resulting from limestone deposits react with the water to produce OH- ions, according to the equation:

{\text{HC}}{{\text{O}}_{\text{3}}}^{\text{ - }}{\text{  +  }}{{\text{H}}_{\text{2}}}{\text{O}} \to {{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{  +  O}}{{\text{H}}^{\text{ - }}}

As a result, streams and lakes are often basic, with pH values between 7 and 8, sometimes as high as 8.5.

Objectives

In this experiment, you will use a pH Sensor to measure the pH of a body of water.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Earth Science with Vernier »

Earth Science with Vernier

See other experiments from the lab book.

1Introduction to Data Collection
2Exploring Magnetism
3Where IS North?
4Searching for Iron Ore
5Sea Floor Spreading
6Soil pH
7Soil Salinity
8Soil and Acid Rain
9Soil Temperature
10Temperature
11pH
12Turbidity
13Total Dissolved Solids
14Water Treatment
15Salinity of Ocean Water
16Acid Rain and Its Effect on Surface Water
17Freezing of Ocean Water
18Desalination
19Mapping the Ocean Floor
20Are All Sunglasses Created Equal?
21Comparing Sunscreens
22UV Light and Clothing
23Reflection and Absorption of Light
24The Greenhouse Effect
25Land and Sea Breezes
26Relative Humidity
27Dew Point
28Wind Chill
29Seasons and Angle of Insolation
30Fossil Fuels
31Solar Homes
32Photovoltaic Cells
33Wind Power
P1Air Temperature
P2Air Temperature and Relative Humidity
P3Ground Temperature
P4Barometric Pressure
P5Measuring Particulates
P6Weather Stations

Experiment 11 from Earth Science with Vernier Lab Book

<em>Earth Science with Vernier</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

Buy the Book

Go to top