Question

Is each of the following statements true or false? (a) All strong acids contain one or more \(\mathrm{H}\) atoms. (b) A strong acid is a strong electrolyte. (c) A \(1.0-M\) solution of a strong acid will have \(\mathrm{pH}=1.0\).

Short answer

(a) True - All strong acids contain one or more \(H\) atoms. (b) True - A strong acid is a strong electrolyte. (c) False - A 1.0-M solution of a strong acid will have \(pH = 0\), not 1.0.

Step-by-step solution

Statement (a) - Determine if all strong acids contain one or more H atoms

All strong acids are capable of donating one or more protons (\(H^+\)) to a solution. These protons are present in the acid as hydrogen atoms. Therefore, for an acid to be classified as a strong acid, it must contain one or more hydrogen atoms. Thus, this statement is \(\underline{\text{True}}\).

Statement (b) - Determine if a strong acid is a strong electrolyte

A strong electrolyte is a substance that can completely dissociate into its constituent ions when dissolved in a solvent. Strong acids can completely dissociate into their constituent ions in water, producing a high concentration of \(H^+\) ions. Therefore, strong acids are strong electrolytes. Thus, this statement is \(\underline{\text{True}}\).

Statement (c) - Determine if a 1.0-M solution of a strong acid will have pH=1.0

To analyze this statement, let's calculate the pH of a 1.0 M solution of a strong acid. We know that the pH of a solution is calculated as follows: \[pH = -\log_{10} [H^+]\] For a 1.0 M solution of a strong acid, it completely dissociates in water, and the concentration of \(H^+\) ions is 1.0 M. So, \[pH = -\log_{10} (1.0)\] The logarithm of 1 is 0, so the pH becomes: \[pH = -\log_{10} (1.0) = 0\] Therefore, a 1.0 M solution of a strong acid will have a pH of 0, not 1.0. Thus, this statement is \(\underline{\text{False}}\).

Key concepts

Chemical Properties of Acids

Acids are compounds that exhibit a certain set of chemical behaviors, primarily characterized by their ability to donate protons, which are hydrogen ions (\(H^+\)), to other substances. This chemical property is known as acidity. An essential attribute of a strong acid, such as hydrochloric acid (\(HCl\)), is its willingness to release these protons when dissolved in water. This results in the characteristic sour taste and acidic pH they exhibit.

Due to their proton-donor nature, acids react with bases to form water and salts in neutralization reactions. They can also react with metals to produce hydrogen gas and a salt. Their reactivity with indicators, like litmus paper, which turns red in an acidic environment, provides an uncomplicated method to identify their presence. Additionally, the concentration of hydrogen ions they liberate is directly tied to their corrosive nature; the more ions, the stronger the acid and the more profound its corrosive effects.

Acid Strength and Electrolytes

The strength of an acid is an indicator of its ability to dissociate into ions in water. Strong acids are considered strong electrolytes because they completely dissociate into their constituent ions, leading to a solution that is an excellent conductor of electricity. When dissolved, these acids release a high concentration of hydrogen ions (\(H^+\)) and their corresponding anions, like chloride (\(Cl^-\)) in the case of hydrochloric acid.

Strong electrolytes, like strong acids, thus allow solutions to carry an electric current more effectively. The degree of dissociation is an important factor that distinguishes strong acids from weak acids. Weak acids, unlike strong acids, do not ionize completely, which results in a lower conductivity in solution and weaker acidity.

pH Calculation

The pH scale offers a quantitative way to express the acidity or basicity of a solution. It is calculated as the negative logarithm of the hydrogen ion concentration (\(pH = -\text{log}_{10} [H^+]\)). For strong acids, which dissociate completely in water, the pH can be determined by simply taking the negative logarithm of their molarity. However, in practice, the pH of a 1.0 M solution of a strong acid is not 1.0 but rather 0, because the \text{log}\text{arithm} of 1 is 0. This straightforward calculation provides insight into the acidity of a solution: the lower the pH, the higher the acidity.

Dissociation of Acids

Dissociation is a chemical process in which molecules or ionic compounds split into smaller particles such as atoms, ions, or radicals, usually in a reversible manner. For strong acids, dissociation is a one-way process in water. This means they release all their hydrogen atoms as protons (\(H^+\)) in an aqueous solution. For example, hydrochloric acid (\(HCl\)) dissociates completely into hydrogen ions and chloride ions (\(Cl^-\)).

The dissociation equation for hydrochloric acid is as follows:
\(HCl \rightarrow H^+ + Cl^-\)
This behavior contrasts with weak acids, which establish an equilibrium between the undissociated and dissociated forms of the acid, meaning they do not release all available hydrogen ions into solution. The complete dissociation of strong acids results in a higher concentration of available protons in the solution, which significantly affects the pH and leads to the acid's strong reactive nature.