Problem 55 - Chemistry and Chemical Reactivity

Question

A table wine has a pH of \(3.40 .\) What is the hydrogen ion concentration of the wine? Is it acidic or basic?

Step-by-Step Solution

Answer

The hydrogen ion concentration is approximately \(3.98 \times 10^{-4} \text{ M}\). The wine is acidic.

Step 1: Understanding the pH concept

pH is a measure of the acidity or basicity of a solution. The pH scale ranges from 0 to 14, where a pH less than 7 indicates an acidic solution, a pH of 7 is neutral, and a pH greater than 7 indicates a basic or alkaline solution.

Step 2: Recognizing the given pH

In the problem, we are given that the pH of the wine is 3.40. This information will help us calculate the hydrogen ion concentration.

Step 3: Using the pH formula

The pH of a solution is defined as the negative logarithm of the hydrogen ion concentration, given by the formula: \( \text{pH} = -\log[H^+] \). We need to rearrange this formula to solve for the hydrogen ion concentration \([H^+]\).

Step 4: Calculating hydrogen ion concentration

To find \([H^+]\), we rearrange the formula to: \([H^+] = 10^{-\text{pH}}\). Substituting the given pH value, \([H^+] = 10^{-3.40}\).

Step 5: Performing the calculation

Calculate \([H^+]\) by evaluating: \([H^+] = 10^{-3.40} \approx 3.98 \times 10^{-4} \text{M}\). This is the hydrogen ion concentration in the wine.

Step 6: Determining if the solution is acidic or basic

Since the pH of the wine is 3.40, which is less than 7, we conclude that the wine is acidic.

Key Concepts

Hydrogen Ion Concentration

Hydrogen ion concentration is a crucial concept in chemistry that helps us understand the acidity or basicity of solutions. It's represented by \([H^+]\) and refers to the amount of hydrogen ions present in a solution. This concentration determines the solution's pH level.

The relationship between \([H^+]\) and pH is given by the formula:

• \( \text{pH} = -\log[H^+] \)

By rearranging the formula, we can find the hydrogen ion concentration if we know the pH:

• \([H^+] = 10^{-\text{pH}}\)

This means the pH value is essentially a logarithmic scale that reflects how much hydrogen ions are in a solution. For example, in the case of a wine with a pH of 3.40, the hydrogen ion concentration is \([H^+] = 10^{-3.40} \approx 3.98 \times 10^{-4} \text{M}\), which indicates a high concentration of hydrogen ions, characteristic of an acidic solution.
Understanding the hydrogen ion concentration in solutions is integral for fields such as environmental science, medicine, and chemical engineering.

Acidic Solutions

Acidic solutions are those with a higher concentration of hydrogen ions than hydroxide ions. On the pH scale, these solutions have a pH lower than 7.

In an acidic solution, the abundance of hydrogen ions \([H^+]\) leads to several unique properties, such as:

• Corrosive nature, which can affect metals and organic materials.
• Tart taste, common in foods and beverages like citrus fruits and vinegar.
• Ability to conduct electricity due to the presence of free ions.

For instance, if we consider a wine with a pH of 3.40, it's classified as acidic. This means it has a substantial amount of hydrogen ions making it slightly tart. The lower the pH, the more acidic the solution is, and each integer decrement in pH represents a tenfold increase in hydrogen ion concentration.
Acidic solutions are not only seen in food products but also play a vital role in industry and biological processes. They are used in cleaning agents, laboratory tests, and even human digestion.

pH Scale

The pH scale is a numeric scale used to specify the acidity or basicity of an aqueous solution. It ranges from 0 to 14.

Key points about the pH scale include:

• A pH of 7 is neutral, meaning the concentration of hydrogen ions is equal to the concentration of hydroxide ions \([OH^-]\).
• pH values less than 7 indicate an acidic solution, with more hydrogen ions present than hydroxide ions.
• pH values greater than 7 signify a basic or alkaline solution, where hydroxide ions outnumber hydrogen ions.

The pH scale is logarithmic, which means each whole number change on the scale represents a tenfold change in hydrogen ion concentration. For instance, a pH of 3 is ten times more acidic than a pH of 4. So, when a wine has a pH of 3.40, it's clearly on the acidic side, reinforcing how small changes in pH can imply significant differences in ion concentration.
This scale is vital in chemistry, biology, environmental science, and various industrial applications, as it helps in monitoring and controlling various processes and reactions.