Problem 49 - Chemistry: An Atoms-Focused Approach

Question

Give the formulas of two strong bases and two weak bases.

Step-by-Step Solution

Answer

Question: Provide the formulas for two strong bases and two weak bases. Answer: Two strong bases are Sodium Hydroxide (NaOH) and Potassium Hydroxide (KOH). Two weak bases are Ammonia (NH3) and Methylamine (CH3NH2).

Step 1: 1. Sodium Hydroxide (NaOH)

NaOH is a strong base, as it dissociates completely in water, producing a high concentration of hydroxide ions (OH-). It is formed by the alkali metal sodium (Na) bonded to a hydroxide ion (OH-). The formula for Sodium Hydroxide is NaOH.

Step 2: 2. Potassium Hydroxide (KOH)

KOH is another strong base that dissociates completely in water, also producing a high concentration of hydroxide ions (OH-). It is formed by the alkali metal potassium (K) bonded to a hydroxide ion (OH-). The formula for Potassium Hydroxide is KOH. - Weak Bases:

Step 3: 1. Ammonia (NH3)

Ammonia is a weak base that does not dissociate completely in water. Instead, it forms ammonium ions (NH4+) and hydroxide ions (OH-) in an equilibrium reaction that does not proceed very far forward. Ammonia has nitrogen and hydrogen atoms covalently bonded in its molecular structure, with the formula NH3.

Step 4: 2. Methylamine (CH3NH2)

Methylamine is another weak base, typically found in organic chemistry. It also does not dissociate completely in water, similarly forming an equilibrium with its conjugate acid and hydroxide ions. The structure of Methylamine includes nitrogen bonded to a methyl group (CH3) and hydrogen atom. The formula for Methylamine is CH3NH2.

Key Concepts

Sodium Hydroxide

Sodium hydroxide, commonly known by its chemical formula NaOH, is a strong base. What makes NaOH a strong base is its ability to dissociate completely in water. This means that when you dissolve sodium hydroxide in water, it breaks apart entirely into sodium ions (Na+) and hydroxide ions (OH-). The release of hydroxide ions is exactly what gives NaOH that strong basic property, leading to a high pH in solutions.

• Dissociation: \[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \]
• Applications: Due to its powerful reactivity, sodium hydroxide is widely used in industry, for example, in soap making, paper manufacturing, and chemical production.

Understanding the dissociation of NaOH helps explain why it's used to neutralize acids in various processes.

Potassium Hydroxide

Like sodium hydroxide, potassium hydroxide (KOH) is also a strong base. It dissociates completely in water which releases potassium ions (K+) and hydroxide ions (OH-). This full dissociation results in a high concentration of hydroxide ions, contributing to its strong base character.

• Dissociation: \[ \text{KOH} \rightarrow \text{K}^+ + \text{OH}^- \]
• Uses: Potassium hydroxide is used in the production of biodiesel, soft soap, and as an electrolyte in alkaline batteries.

The functionality of KOH in diverse applications underscores its importance in both industrial and chemical processes.

Ammonia

Ammonia, with its chemical formula NH3, is categorized as a weak base. Unlike strong bases, ammonia does not dissociate completely in water. It forms a small amount of ammonium ions (NH4+) and hydroxide ions (OH-), establishing an equilibrium that greatly favors the un-ionized form.

• Equilibrium Reaction: \[ \text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
• Functional Role: Ammonia is extensively used in fertilizers, cleaning agents, and in industries as a refrigerant.

Despite being a weak base, ammonia plays an essential role in various chemical processes. Its capability for forming equilibrium with water is key to understanding weak base behavior.

Methylamine

Methylamine (CH3NH2) is a weak organic base similar to ammonia. It does not dissociate completely in water and forms an equilibrium between methylammonium ions (CH3NH3+) and hydroxide ions (OH-), like ammonia.

• Equilibrium Reaction: \[ \text{CH}_3\text{NH}_2 + \text{H}_2\text{O} \rightleftharpoons \text{CH}_3\text{NH}_3^+ + \text{OH}^- \]
• Applications: Methylamine is important in organic synthesis. It's used in the production of pharmaceuticals, agricultural chemicals, and dyes.

Understanding methylamine helps grasp the behavior of weak bases in organic chemistry. Its mild basicity and equilibrium tendencies highlight the complexity of weak base systems.