Vernier Software & Technology

# Conducting Solutions

## Introduction

In this experiment, you will study the electrical conductivity of water and various water solutions. A solution can contain molecules, ions, or both. Some substances, such as sucrose (C12H22O11) and glucose (C6H12O6), dissolve to give a solution containing mostly molecules. An equation representing the dissolving of sucrose (table sugar) in water is:

${{\text{C}}_{{\text{12}}}}{{\text{H}}_{{\text{22}}}}{{\text{O}}_{{\text{11}}}}{\text{(s)}} \leftrightarrow {{\text{C}}_{{\text{12}}}}{{\text{H}}_{{\text{22}}}}{{\text{O}}_{{\text{11}}}}{\text{(aq)}}$

where (s) refers to a solid substance and (aq) refers to a substance dissolved in water. Other substances, such as calcium chloride (CaCl2), dissolve in water to produce a solution containing mostly ions. An equation is:

${\text{CaC}}{{\text{l}}_{\text{2}}}{\text{(s) }} \leftrightarrow {\text{ C}}{{\text{a}}^{{\text{2 + }}}}{\text{(aq) + 2C}}{{\text{l}}^{\text{ - }}}{\text{(aq)}}$

Calcium ions are necessary for muscle contraction, mitochondrial activity, bone formation, and many other metabolic processes. Organisms may obtain minerals such as calcium from their water supply, since ions dissolve in water.

You will determine conductivity of the solutions using a computer-interfaced Conductivity Probe. The unit of conductivity in this experiment is microsiemens per centimeter, or µS/cm.

## Objectives

In this experiment, you will

• Write equations for the dissolving of substances in water.
• Use a Conductivity Probe to test the electrical conductivity of solutions.
• Determine whether molecules or ions are responsible for electrical conductivity of solutions.

## Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

### Option 2

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

## Biology with Vernier

See other experiments from the lab book.

 1 Energy in Food 2 Limitations on Cell Size: Surface Area to Volume 3 Acids and Bases 4 Diffusion through Membranes 5 Conducting Solutions 6A Enzyme Action: Testing Catalase Activity 6B Enzyme Action: Testing Catalase Activity 7 Photosynthesis 8 The Effect of Alcohol on Biological Membranes 9 Biological Membranes 10 Transpiration 11A Cell Respiration (O2) 11B Cell Respiration (CO2) 11C Cell Respiration (Pressure) 11D Cell Respiration (CO2 and O2) 12A Respiration of Sugars by Yeast 12B Sugar Fermentation 13 Population Dynamics 14 Interdependence of Plants and Animals 15 Biodiversity and Ecosystems 16A Effect of Temperature on Respiration 16B Effect of Temperature on Fermentation 17 Aerobic Respiration 18 Acid Rain 19 Dissolved Oxygen in Water 20 Watershed Testing 21 Physical Profile of a Lake 22 Osmosis 23A Effect of Temperature on Cold-Blooded Organisms 23B Effect of Temperature on Cold-Blooded Organisms 24A Lactase Action 24B Lactase Action 25 Primary Productivity 26 Control of Human Respiration 27 Heart Rate and Physical Fitness 28 Monitoring EKG 29 Ventilation and Heart Rate 30 Oxygen Gas and Human Respiration 31A Photosynthesis and Respiration (O2) 31B Photosynthesis and Respiration (CO2) 31C Photosynthesis and Respiration (CO2 and O2)

### Experiment 5 from Biology with Vernier Lab Book

#### 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.