Question

Determine the acid and base that were neutralized to produce each of the following salts: (a) sodium fluoride, \(\operatorname{NaF}(a q)\) (b) magnesium iodide, \(\operatorname{MgI}_{2}(a q)\) (c) calcium nitrate, \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}(a q)\) (d) lithium carbonate, \(\mathrm{Li}_{2} \mathrm{CO}_{3}(a q)\)

Short answer

(a) NaOH and HF, (b) Mg(OH)₂ and HI, (c) Ca(OH)₂ and HNO₃, (d) LiOH and H₂CO₃.

Step-by-step solution

Identify Component Ions

Break down each salt into its respective ions. For example, sodium fluoride, \( \text{NaF} \), breaks into \( \text{Na}^+ \) and \( \text{F}^- \) ions.

Determine the Acid

Determine the acid that contributes the anion. For \( \text{F}^- \), the corresponding acid is hydrofluoric acid, \( \text{HF} \). Repeat this for other salts: \( \text{HI} \) for \( \text{I}^- \), \( \text{HNO}_3 \) for \( \text{NO}_3^- \), and \( \text{H}_2\text{CO}_3 \) for \( \text{CO}_3^{2-} \).

Determine the Base

Determine the base from which the cation is derived. For example, \( \text{Na}^+ \) comes from sodium hydroxide, \( \text{NaOH} \). For others: \( \text{Mg}^2+ \) comes from \( \text{Mg(OH)}_2 \), \( \text{Ca}^2+ \) comes from \( \text{Ca(OH)}_2 \), and \( \text{Li}^+ \) comes from \( \text{LiOH} \).

Combine Acid and Base

Combine the identified acid and base for each salt. For example, sodium fluoride \( \text{NaF} \) results from \( \text{HF} \) and \( \text{NaOH} \). Similarly, \( \text{MgI}_2 \) comes from \( \text{HI} \) and \( \text{Mg(OH)}_2 \), \( \text{Ca(NO}_3)_2 \) comes from \( \text{HNO}_3 \) and \( \text{Ca(OH)}_2 \), and \( \text{Li}_2\text{CO}_3 \) comes from \( \text{H}_2\text{CO}_3 \) and \( \text{LiOH} \).

Key concepts

Acid-Base Reactions

In chemistry, an acid-base reaction is a fundamental concept where an acid and a base interact with each other. This action results in the exchange of ions to form a new compound. When an acid meets a base, they undergo a chemical change in which the acid donates a proton (typically a hydrogen ion, \( \text{H}^+ \)) to the base. Acids generally taste sour and can turn blue litmus paper to red, indicating their acidic nature. Bases, on the other hand, taste bitter and feel slippery, having the ability to turn red litmus paper blue.

A quintessential outcome of these reactions is the formation of water molecules and an ionic compound known commonly as a salt. This type of reaction is exothermic, meaning it releases heat, which is often felt as warmth, especially when concentrated acids and bases are mixed. Understanding this basic interaction is critical as it forms the basis for more complex chemical equations and reactions in chemistry.

Neutralization

Neutralization is an essential process in chemistry where an acid reacts with a base to produce water and a salt. This type of reaction balances out the acidic and basic properties of the reactants, leading to a neutral solution. An example of this is when hydrochloric acid (\(\text{HCl}\)) reacts with sodium hydroxide (\(\text{NaOH}\)). The resulting products are water and sodium chloride (\(\text{NaCl}\)), a common table salt.

In a complete neutralization reaction, the amount of acid equals the amount of base, thus cancelling out each other's properties. Knowing how to predict the products of neutralization reactions is a valuable skill in chemistry, especially in laboratory settings and industrial applications where such reactions help control pH levels. The concept is widely applied in titrations, a method used to determine the concentration of an acid or a base in a solution through controlled neutralization.

Ionic Compounds

Ionic compounds are a class of chemical compounds made up of ions that are held together through ionic bonds. These compounds typically form when metals react with nonmetals. In an ionic bond, electrons are transferred from one atom to another, creating ions. A positively charged ion, or cation, is formed from the metal, and a negatively charged ion, or anion, is formed from the nonmetal.

The unique electrostatic attraction between these oppositely charged ions gives ionic compounds their distinct characteristics, such as high melting and boiling points and the ability to conduct electricity when melted or dissolved in water. Famous examples include sodium chloride (\(\text{NaCl}\)) and calcium carbonate (\(\text{CaCO}_3\)). Understanding ionic compounds is instrumental in mastering concepts related to chemical bonding and reactions.

Salt Formation

Salt formation is a crucial product of acid-base chemistry. A salt is created when the hydrogen ion from an acid is replaced by a metal ion from a base. The general form of this reaction can be shown as: \(\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}\).

For instance, when sodium hydroxide (a base) reacts with hydrochloric acid, it forms sodium chloride, which is common table salt. Salt formation can occur in various ways, such as direct reaction of an acid and base, or through other methods like evaporation or crystallization from a solution containing ions. It is important to recognize salts not only as table salts but also as compounds with wide-ranging industrial applications, from fertilizers to food preservation.

Learning about salt formation broadens the understanding of chemical interactions and supports the grasp of larger concepts in chemistry like synthesis reactions and solution chemistry.