A solution of salt in water conducts electricity, but a solution of sugar does not. Explain why.

In the realm of chemistry, understanding the differences between ionic and covalent bonds is crucial for explaining phenomena such as electrical conductivity in solutions.

What are Ionic Bonds?
Ionic bonds represent the electrostatic attraction between oppositely charged ions typically formed when a metal and a nonmetal interact. As one atom (the metal) loses one or more electrons, becoming a positively charged ion or cation, and another atom (the nonmetal) gains these electrons, becoming a negatively charged ion or anion, an ionic bond is formed. Take common table salt, or sodium chloride (NaCl) as an example; it consists of sodium ions (Na+) and chloride ions (Cl-), held together by this ionic bonding.

What are Covalent Bonds?
Covalent bonds, on the other hand, involve the sharing of electron pairs between atoms, typically nonmetals. This sharing allows each atom to achieve a full outer shell of electrons, leading to a stable molecule. An example is sucrose, or table sugar (C₁₂H₂₂O₁₁), where the atoms are covalently bonded and there is no formation of ions.

The key takeaway is that the ionic compounds dissociate into ions when dissolved in water, facilitating the conductance of electricity, whereas covalent compounds do not.

The concept of dissociation is central when examining why certain solutions conduct electricity and others do not.

What Happens During Dissociation?
When ionic compounds like salt are dissolved in water, they undergo a process called dissociation. This process is the separation of the compound into individual ions. These ions are surrounded by water molecules, a situation referred to as hydration. In this state, they are mobilized and can move freely through the solution.

As these ions move, they carry with them their electrical charge. It is this movement of charges that allows the solution to conduct electricity. Without dissociation, as is the case with covalent substances like sugar, there are no charges free to move through the solution, and therefore, the ability to conduct electricity is not present.

Understanding the distinction between electrolytes and nonelectrolytes sheds light on the electrical properties of solutions.

Electrolytes: are substances that, when dissolved in water, produce a solution that can conduct electricity due to the presence of free ions. These can be strong electrolytes, which dissociate completely into ions, or weak electrolytes, which only partially dissociate. Salts like sodium chloride (NaCl) are typical examples of strong electrolytes.

Nonelectrolytes: do not dissociate into ions when dissolved in water. As a result, their solutions cannot conduct electricity. Examples of nonelectrolytes include most organic compounds, such as sugar (sucrose).

The key factor that determines the ability of a solution to conduct electricity is the presence of ions. Electrolytes provide these ions, thus creating a conductive path, while nonelectrolytes, in the absence of ions, do not contribute to the conductivity of the solution.