Question

Indicate whether aqueous solutions of the following substances contain ions. If so, write formulas for the ions in solution. (a) \(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) (glucose) (b) \(\mathrm{CH}_{4}\) (c) \(\mathrm{NaCl}\)

Short answer

Glucose and methane do not form ions when in solution. Sodium chloride dissociates into sodium (\(\mathrm{Na}^{+}\)) and chloride (\(\mathrm{Cl}^{-}\)) ions in solution.

Step-by-step solution

Identify properties of the compounds

Firstly, you have to know that glucose and methane are covalent compounds, while sodium chloride is an ionic compound.

Recognize behavior of Covalent Compounds

Covalent compounds (like glucose and methane) do not generally form ions when dissolved in water. They remain as neutral molecules.

Recognize behavior of Ionic Compounds

Ionic compounds (like sodium chloride) do form ions when dissolved in water. They dissociate into their constituent ions.

Identify ions in solution for glucose

Considering the previous steps, glucose (\(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\)) does not form ions in solution.

Identify ions in solution for methane

Similarly, methane (\(\mathrm{CH}_{4}\)) does not form ions in solution.

Identify ions in solution for sodium chloride

Sodium chloride (\(\mathrm{NaCl}\)), however, dissociates into the sodium ion (\(\mathrm{Na}^{+}\)) and the chloride ion (\(\mathrm{Cl}^{-}\)) when in solution.

Key concepts

Covalent Compounds in Water

Understanding how covalent compounds behave in water is essential for students studying chemistry. These compounds, such as glucose ((C_{6}H_{12}O_{6})) and methane ((CH_{4})), consist of atoms bonded together by sharing electrons. When they dissolve in water, they do not break into ions. Instead, they spread out uniformly in the solution as individual molecules. This means that a solution of glucose or methane in water does not contain charged particles, or ions, but rather molecules dispersed throughout the solvent.

It's this lack of ions that distinguishes covalent compounds from ionic ones in aqueous solutions. When these compounds are in water, they often exhibit different properties like not conducting electricity, which is due to the absence of charged particles necessary for the movement of electric current.

Ionic Compounds in Water

When ionic compounds like sodium chloride ((NaCl)) dissolve in water, they exhibit a distinctive behavior known as dissociation. This process involves the separation of the compound into its positive and negative ions. An ionic compound is composed of anions and cations held together by electrostatic forces. In water, these forces are weakened, allowing the ions to disperse throughout the solution.

Dissolving an ionic compound in water significantly changes its properties, such as increasing the solution's ability to conduct electricity. This is because the ions that result from dissociation can move freely and carry charge, enabling the movement of electric current through the solution. The degree of dissociation and the types of ions produced are crucial for understanding the chemical behavior of these solutions.

Dissociation of Sodium Chloride

Here is a closer look at a common example of ionic compounds in action: the dissociation of sodium chloride ((NaCl)) in water. When (NaCl) dissolves, it separates into sodium ions ((Na^{+})) and chloride ions ((Cl^{-})). This simple yet illustrative example is key to understanding solubility and electrical conductivity in aqueous solutions.

The presence of (Na^{+}) and (Cl^{-}) is easy to detect through various chemical tests and is fundamentally important for numerous biological and industrial processes. For instance, the sodium ion is crucial for nerve impulse transmission, while the chloride ion plays a vital role in maintaining the balance of fluids in our bodies.

Properties of Compounds

When studying the properties of compounds, it is crucial to differentiate between ionic and covalent compounds. The properties such as melting points, boiling points, solubility, and electrical conductivity can vary greatly depending upon the type of compound.

For example, ionic compounds typically have higher melting and boiling points due to the strong electrostatic forces between ions. They also tend to be soluble in polar solvents like water and are conductive when dissolved or melted. Covalent compounds, on the other hand, may have lower melting and boiling points and often do not conduct electricity in solution. These distinctions are important for predicting the behavior of substances in different scenarios and for understanding their role in chemical reactions.