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), 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)}} \to {{\text{C}}_{{\text{12}}}}{{\text{H}}_{{\text{22}}}}{{\text{O}}_{{\text{11}}}}{\text{(aq)}}

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)}} \to {\text{C}}{{\text{a}}^{{\text{2 + }}}}{\text{(aq) + 2 C}}{{\text{l}}^{\text{ - }}}{\text{(aq)}}

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 which, molecules or ions, are responsible for electrical conductivity of solutions.