- \(HCl\) donates a proton to become \(Cl^{-}\), so \(HCl\) is an acid.
- \(C_5H_5N\) accepts a proton to become \(HC_5H_5N^{+}\), so \(C_5H_5N\) is a base.
- \(Cl^{-}\) is the product of the acid, serving as the conjugate base.
- \(HC_5H_5N^{+}\) is the product of the base, serving as the conjugate acid.
- Final Labels: \(HCl\) (Acid), \(C_5H_5N\) (Base), \(Cl^-\) (Base), \(HC_5H_5N^+\) (Acid).
Explanation
- Analysis of the Chemical Reaction
The Brønsted-Lowry theory defines an acid as a substance that can donate a proton (\(H^+\)) and a base as a substance that can accept a proton (\(H^+\)). In any chemical reaction, species are identified as acids or bases based on whether they donate or accept a proton when transitioning from the reactants to the products. We are looking at the equation:
\[HCl + C_5H_5N \rightleftharpoons Cl^{-} + HC_5H_5N^{+}\]
We will examine the transformation of each species to determine their roles.
- Identifying Reactants
Looking at the reactant side, we see \(HCl\) and \(C_5H_5N\).
- \(HCl\) transforms into \(Cl^{-}\) by losing a hydrogen ion (\(H^+\)). Since it donated a proton, \(HCl\) acts as an acid.
- \(C_5H_5N\) transforms into \(HC_5H_5N^{+}\) by gaining a hydrogen ion (\(H^+\)). Since it accepted a proton, \(C_5H_5N\) acts as a base.
- Identifying Products and Conjugates
Now we examine the products to determine their conjugate roles:
- The product \(Cl^{-}\) is formed after \(HCl\) donates its proton. Therefore, \(Cl^{-}\) acts as the conjugate base.
- The product \(HC_5H_5N^{+}\) is formed after \(C_5H_5N\) accepts a proton. Therefore, \(HC_5H_5N^{+}\) acts as the conjugate acid.
- Final Classification
Mapping the labels to the original equation \(HCl + C_5H_5N \rightleftharpoons Cl^{-} + HC_5H_5N^{+}\):
- \(HCl\): Acid
- \(C_5H_5N\): Base
- \(Cl^{-}\): Base (conjugate base)
- \(HC_5H_5N^{+}\): Acid (conjugate acid)
All species are classified based on their proton-transfer behavior. The roles are:
- \(HCl\): Acid
- \(C_5H_5N\): Base
- \(Cl^{-}\): Base
- \(HC_5H_5N^{+}\): Acid
Examples
In real-life chemistry, understanding acid-base reactions is crucial for everything from balancing the pH in swimming pools to industrial processes like creating medicines. For instance, when you take an antacid to relieve heartburn, it works by acting as a base that accepts excess protons (\(H^+\)) from the acidic stomach fluid, neutralizing the acidity. This simple proton transfer, just like the one in our equation, is the fundamental principle behind many neutralization processes that keep our bodies and environment in balance.