Question

Write the conjugate acid for each of the following. a. \(\mathrm{NH}_{3}\) b. \(\mathrm{NH}_{2}^{-}\) c. \(\mathrm{H}_{2} \mathrm{O}\) d. \(\mathrm{OH}^{-}\)

Short answer

The conjugate acids of the given compounds are as follows: a. \(\mathrm{NH}_{4}^{+}\) b. \(\mathrm{NH}_{3}\) c. \(\mathrm{H}_{3} \mathrm{O}^{+}\) d. \(\mathrm{H}_{2} \mathrm{O}\)

Step-by-step solution

Add a proton to the given formula

Add an H⁺ ion to the formula for ammonia, \(\mathrm{NH}_{3}\), to get the conjugate acid.

Adjust the charge if necessary

In this case, no adjustment of the charge is required. The conjugate acid is \(\mathrm{NH}_{4}^{+}\). b. Conjugate acid of \(\mathrm{NH}_{2}^{-}\)

Add a proton to the given formula

Add an H⁺ ion to the formula for the amide ion, \(\mathrm{NH}_{2}^{-}\), to get the conjugate acid.

Adjust the charge if necessary

Since the amide ion has a negative charge, adding the proton will neutralize the charge. The conjugate acid is \(\mathrm{NH}_{3}\). c. Conjugate acid of \(\mathrm{H}_{2} \mathrm{O}\)

Add a proton to the given formula

Add an H⁺ ion to the formula for water, \(\mathrm{H}_{2} \mathrm{O}\), to get the conjugate acid.

Adjust the charge if necessary

Water is a neutral species, so adding a proton creates a positive charge. The conjugate acid is \(\mathrm{H}_{3} \mathrm{O}^{+}\). d. Conjugate acid of \(\mathrm{OH}^{-}\)

Add a proton to the given formula

Add an H⁺ ion to the formula for the hydroxide ion, \(\mathrm{OH}^{-}\), to get the conjugate acid.

Adjust the charge if necessary

Since the hydroxide ion has a negative charge, adding the proton will neutralize the charge. The conjugate acid is \(\mathrm{H}_{2} \mathrm{O}\).

Key concepts

Acids and Bases

Understanding acids and bases is essential for grasping a wide range of chemical processes. In chemistry, acids are substances that can donate a proton (or hydrogen ion, H⁺) to another substance. Bases, on the other hand, are substances that can accept a proton. These definitions stem from the Brønsted-Lowry theory, which presents one of the most widely used frameworks to describe their behavior.

A key idea within this theory is the notion of conjugate acid-base pairs. When an acid donates a proton, it transforms into its conjugate base. Conversely, when a base accepts a proton, it becomes its conjugate acid. This means that acids and bases always exist in pairs, where a base becomes an acid after gaining a proton.

• An important aspect to remember is that acids increase the concentration of hydrogen ions in a solution, while bases decrease it.
• Acid strength is often associated with its ability to donate protons, while base strength relates to its propensity to accept protons.

Recognizing conjugate acid-base pairs is vital for understanding how acids and bases interact, especially during chemical reactions.

Chemical Reactions

Chemical reactions involving acids and bases often involve the transfer of protons between molecules. This process fundamentally changes the molecules involved. One especially notable type of reaction is a neutralization reaction, where an acid and a base react to form water and a salt.

These reactions are crucial in various real-world applications, such as manufacturing, digestion, and chemical synthesis.

• Neutralization reactions help to keep pH levels balanced, which is essential in biological and environmental systems.
• Proton transfer is a common feature in these reactions, emphasizing the dynamic nature of acids and bases converting into their conjugate counterparts.

Understanding these reactions helps to predict the behavior and properties of a substance under different conditions.

Proton Transfer

Proton transfer is a central concept in the study of acids and bases, involving the movement of protons (H⁺ ions) from one molecule to another. This transfer is what turns basic molecules into their conjugate acids, and acidic molecules into their conjugate bases.

The process of proton transfer can be influenced by various factors, including the strength of the acid or base, the polarity of the solvent, and the temperature.

• Typically, strong acids will more readily donate protons compared to weak acids, making proton transfer more frequent.
• The process itself is a core mechanism behind many biological and chemical processes, such as enzyme function and metabolism.

By grasping the principles of proton transfer, students and chemists can predict and manipulate reactions, leading to newer innovations in science and industry.