Question

Write the formula of the conjugate base of each acid. (a) \(\mathrm{HNO}_{2}\) (b) \(\mathrm{HF}\) (c) \(\mathrm{H}_{3} \mathrm{BO}_{3}\)

Short answer

The conjugate base of (a) HNO2 is NO2-. (b) HF is F-. (c) H3BO3 is H2BO3-.

Step-by-step solution

Find the Conjugate Base of HNO2

Firstly, an acid donates a proton (H+). When HNO2 loses a proton, it becomes NO2-. So, the conjugate base of HNO2 is NO2-.

Find the Conjugate Base of HF

When HF donates a proton, only 'F-' remains. So, the conjugate base of HF is F-.

Find the Conjugate Base of H3BO3

H3BO3 will lose a proton to become H2BO3-. Thus, the conjugate base of H3BO3 is H2BO3-.

Key concepts

Understanding Acid-Base Reactions

Acid-base reactions are a fundamental concept in chemistry. They involve the transfer of protons between substances. In an acid-base reaction, one substance acts as an acid and donates a proton, while the other acts as a base and accepts the proton.
This creates two conjugate pairs:

• The conjugate base comes from the acid after it donates a proton.
• The conjugate acid forms from the base after it gains a proton.

This proton transfer leads to observable changes in the pH and properties of the substances involved. Understanding these reactions helps predict the behavior of acids and bases in different chemical environments. Acid-base reactions are essential in processes like digestion, battery operation, and even maintaining the right pH in swimming pools.

The Role of Proton Donation

Proton donation is a key process in defining acids. According to the Brønsted-Lowry theory, acids donate protons (H⁺ ions) to bases. When an acid donates a proton, it forms its conjugate base. For example, in the equation:\[\text{HA} \rightarrow \text{A}^- + \text{H}^+\]We see the acid \(\text{HA}\) donating a proton to become \(\text{A}^-\), its conjugate base.
Protons are hydrogen atoms missing their electrons, making them highly reactive. This reactivity is crucial for the formation and breaking of bonds during chemical reactions.
Proton donation affects a solution's acidity. As acids donate protons, they lower the concentration of hydronium ions in the solution, effectively increasing its acidity.

Deciphering Chemical Formulas

Chemical formulas are symbolic representations of chemical substances. They are composed of element symbols and numerical subscripts, which indicate the number of each type of atom in a compound.

• The formula tells us which elements are present in a substance.
• The subscript numbers show how many atoms of each element are in each molecule.

For example, \(\mathrm{HNO}_2\) represents nitrous acid, consisting of:

• 1 hydrogen atom (H)
• 1 nitrogen atom (N)
• 2 oxygen atoms (O)

This formula helps predict how the substance will react. When \(\mathrm{HNO}_2\) loses a proton, it becomes \(\mathrm{NO}_2^-\), showing how chemical formulas reveal structural changes during reactions. Understanding these formulas is critical in predicting reaction outcomes and balancing chemical equations.