Calculating Hydronium Concentration And Classifying Acidity Part C And D Chemistry Problem

Hey guys! Today, we're diving deep into the fascinating world of chemistry, specifically focusing on understanding hydroxide ([OH⁻]) and hydronium ([H₃O⁺]) concentrations in solutions. This is a crucial concept in chemistry because it helps us determine whether a solution is acidic, basic, or neutral. So, buckle up and get ready to explore the intricacies of chemical solutions!

Part C [OH⁻] = 4.5 × 10⁻⁹ M: Calculating [H₃O⁺]

Decoding Hydroxide Concentration

Okay, so we're given that the hydroxide concentration, denoted as [OH⁻], is 4.5 × 10⁻⁹ M. What does this tell us? Well, in any aqueous solution (a solution where water is the solvent), there's a delicate balance between hydroxide ions (OH⁻) and hydronium ions (H₃O⁺). These ions are constantly being formed and consumed in a reversible reaction known as the autoionization of water.

Autoionization of Water: Think of it as water molecules playing a game of tag with protons (H⁺). One water molecule donates a proton to another, resulting in the formation of a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). This process happens spontaneously, although to a very small extent.

The equilibrium expression for this reaction is:

K_w = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25°C

This equation is your golden ticket to solving this part of the problem. It states that the product of the hydronium and hydroxide concentrations is always constant at a given temperature (1.0 × 10⁻¹⁴ at 25°C). This constant, Kw, is known as the ion product constant for water. It's like a seesaw – if one side goes up, the other must go down to maintain balance.

Calculating [H₃O⁺] with Precision

Now that we know the [OH⁻] and Kw, we can easily calculate the [H₃O⁺]. We simply rearrange the equation above:

[H₃O⁺] = K_w / [OH⁻]

Plugging in the values:

[H₃O⁺] = (1.0 × 10⁻¹⁴) / (4.5 × 10⁻⁹)

[H₃O⁺] ≈ 2.2 × 10⁻⁶ M

So, the hydronium ion concentration is approximately 2.2 × 10⁻⁶ M. Notice that we've expressed the answer using two significant figures, as requested in the question. Significant figures are important because they reflect the precision of our measurements. In this case, the given hydroxide concentration has two significant figures, so our answer should also have two significant figures.

Why This Matters: The Balance of Acidity and Basicity

Understanding the relationship between [H₃O⁺] and [OH⁻] is crucial for determining the acidity or basicity of a solution. In a neutral solution, the concentrations of hydronium and hydroxide ions are equal ([H₃O⁺] = [OH⁻] = 1.0 × 10⁻⁷ M at 25°C). However, when the concentrations are not equal, the solution is either acidic or basic. As we will see in Part D, this difference determines the nature of the solution.

Part D: Classifying the Solution as Acidic or Basic

The Acid-Base Spectrum

Now, let's tackle the million-dollar question: Is this solution acidic or basic? To answer this, we need to understand the acid-base spectrum. The spectrum is like a sliding scale where we can place different solutions based on their pH values. A pH of 7 is considered neutral, pH values below 7 indicate acidity, and pH values above 7 indicate basicity.

But wait, how does this relate to [H₃O⁺] and [OH⁻]? Well, the pH scale is actually based on the hydronium ion concentration. Specifically, pH is defined as the negative logarithm (base 10) of the hydronium ion concentration:

pH = -log₁₀[H₃O⁺]

A high [H₃O⁺] corresponds to a low pH, indicating an acidic solution. Conversely, a low [H₃O⁺] corresponds to a high pH, indicating a basic solution. This inverse relationship is essential for understanding acid-base chemistry.

Deciphering the Solution's Nature

In Part C, we calculated the hydronium ion concentration to be approximately 2.2 × 10⁻⁶ M. To classify the solution, we can compare this value to the hydronium ion concentration in a neutral solution (1.0 × 10⁻⁷ M). In our case:

[H₃O⁺] (2.2 × 10⁻⁶ M) > [H₃O⁺] (1.0 × 10⁻⁷ M) in neutral solution

Since the hydronium ion concentration in our solution is greater than that in a neutral solution, we can confidently classify this solution as acidic.

Visualizing the Acid-Base Spectrum

Imagine a seesaw again. On one side, we have acidity, driven by a high concentration of H₃O⁺. On the other side, we have basicity, driven by a high concentration of OH⁻. A neutral solution sits perfectly balanced in the middle. Our solution, with its elevated H₃O⁺ level, tips the seesaw towards the acidic side.

Why It's Not Just About Numbers: The Importance of Context

While the math gives us a clear answer (acidic), it's also important to think about the context. In chemistry, understanding the why is just as important as understanding the what. Acidic solutions have a higher concentration of H₃O⁺, which can react with other substances in specific ways. This reactivity is what gives acids their characteristic properties, such as the ability to dissolve certain metals or change the color of indicators.

The Broader Implications: Why This Matters in the Real World

Applications Across Industries

The concepts we've explored today aren't just confined to the chemistry lab. Understanding acidity and basicity is crucial in a wide range of industries, from environmental science to medicine to food production. For instance:

• Environmental Science: The pH of rainwater and soil affects plant growth and the health of aquatic ecosystems. Acid rain, caused by pollutants, can have devastating consequences.
• Medicine: The pH of blood and other bodily fluids is tightly regulated to ensure proper physiological function. Imbalances in pH can indicate underlying medical conditions.
• Food Production: The acidity of food products affects their taste, texture, and preservation. Food scientists carefully control pH to ensure quality and safety.

Acid-Base Chemistry in Daily Life

Even in your daily life, you encounter acid-base chemistry all the time. Think about the tangy taste of lemon juice (acidic) or the slippery feel of soap (basic). The antacids you take for heartburn work by neutralizing excess stomach acid. Understanding these concepts gives you a deeper appreciation for the chemical reactions happening around you.

The Ongoing Quest for Knowledge

Chemistry is a vast and ever-evolving field. The more we learn about the fundamental principles, like acid-base chemistry, the better equipped we are to solve real-world problems and make new discoveries. The concepts we've discussed today are just the tip of the iceberg, but they provide a solid foundation for further exploration.

Conclusion: Mastering the Fundamentals of Chemical Solutions

So, there you have it! We've successfully calculated the hydronium ion concentration ([H₃O⁺]) given the hydroxide ion concentration ([OH⁻]) and classified the solution as acidic. We've also explored the broader implications of acid-base chemistry and its importance in various fields. Remember, chemistry is all about understanding the interactions of matter, and by mastering these fundamental concepts, you're well on your way to becoming a chemistry whiz!

Keep exploring, keep questioning, and most importantly, keep learning! The world of chemistry is full of amazing discoveries waiting to be made.