Calculating POH And Classifying Solutions Acidic Basic Or Neutral

Jul 28, 2025 by ADMIN 66 views

Understanding pOH Calculation and Solution Classification

Hey guys! Today, we're diving into the fascinating world of acid-base chemistry. We'll be tackling a problem that involves calculating the pOH of a solution and classifying it as acidic, basic, or neutral. This is a fundamental concept in chemistry, and understanding it is crucial for grasping more advanced topics. So, let's get started!

Part A: Calculating pOH from [OH-] Concentration

In this part, we're given the hydroxide ion concentration, [OH-], which is 9.5 x 10^-2 M, and our mission is to calculate the pOH. Now, you might be wondering, what exactly is pOH? Well, pOH is a measure of the hydroxide ion concentration in a solution, similar to how pH measures the hydrogen ion concentration. The 'p' in pOH stands for '-log', so the formula for calculating pOH is:

pOH = -log[OH-]

This formula might look a bit intimidating, but don't worry, it's quite straightforward once you get the hang of it. The key here is the logarithm, which is a mathematical function that helps us deal with very large or very small numbers. In this case, the hydroxide ion concentration is a small number (9.5 x 10^-2 M), and the logarithm helps us express it in a more manageable scale.

To calculate the pOH, we simply plug in the given [OH-] value into the formula:

pOH = -log(9.5 x 10^-2)

Now, you can use a calculator to evaluate this expression. Make sure you know how to use the logarithm function on your calculator. The result should be around 1.02. The question asks us to express the answer using two decimal places, so the final answer for the pOH is 1.02.

Therefore, the pOH of the solution is 1.02.

This result tells us something important about the solution. Remember, pOH is a measure of hydroxide ion concentration. A low pOH value, like 1.02, indicates a high concentration of hydroxide ions. This means the solution is likely to be basic, which we'll explore further in the next part.

Why is pOH important in chemistry?

Understanding pOH is crucial for several reasons in chemistry. First, it helps us classify solutions as acidic, basic, or neutral. This is essential for predicting how substances will react with each other. For instance, if we know a solution has a low pOH (high hydroxide ion concentration), we can anticipate that it will readily react with acids.

Second, pOH is related to pH, which is another important measure of acidity and basicity. The sum of pH and pOH is always 14 at 25°C. This relationship allows us to calculate either pH or pOH if we know the other value. For example, if we know the pOH of a solution is 1.02, we can calculate its pH as follows:

pH + pOH = 14 pH = 14 - pOH pH = 14 - 1.02 pH = 12.98

This calculation shows that the solution has a high pH, which further confirms its basic nature. The pH scale ranges from 0 to 14, with values less than 7 indicating acidity, values greater than 7 indicating basicity, and a value of 7 indicating neutrality.

Third, pOH is used in various chemical calculations, such as determining the equilibrium constants for acid-base reactions. These constants help us predict the extent to which a reaction will proceed and the concentrations of reactants and products at equilibrium.

In summary, pOH is a fundamental concept in acid-base chemistry that provides valuable information about the hydroxide ion concentration in a solution and its relationship to acidity, basicity, and chemical reactions. By understanding pOH, we can gain a deeper understanding of the chemical world around us.

Part B: Classifying the Solution

Now that we've calculated the pOH, let's classify the solution as acidic, basic, or neutral. Remember, the pOH scale is inversely related to the pH scale. A low pOH indicates a high concentration of hydroxide ions (OH-), which means the solution is basic. Conversely, a high pOH indicates a low concentration of hydroxide ions, which means the solution is acidic. A pOH of 7 indicates a neutral solution.

We calculated the pOH to be 1.02. This value is significantly lower than 7, indicating a high concentration of hydroxide ions. Therefore, we can classify this solution as basic.

Understanding Acidic, Basic, and Neutral Solutions

To fully grasp why we classified the solution as basic, let's delve deeper into the concepts of acidic, basic, and neutral solutions. These classifications are based on the relative concentrations of hydrogen ions (H+) and hydroxide ions (OH-) in a solution.

Acidic Solutions: Acidic solutions have a higher concentration of hydrogen ions (H+) than hydroxide ions (OH-). When an acid is dissolved in water, it releases H+ ions, increasing the H+ concentration. Examples of acidic solutions include lemon juice, vinegar, and hydrochloric acid.
Basic Solutions: Basic solutions, also known as alkaline solutions, have a higher concentration of hydroxide ions (OH-) than hydrogen ions (H+). When a base is dissolved in water, it releases OH- ions, increasing the OH- concentration. Examples of basic solutions include soap, bleach, and sodium hydroxide.
Neutral Solutions: Neutral solutions have equal concentrations of hydrogen ions (H+) and hydroxide ions (OH-). Pure water is a classic example of a neutral solution. In pure water, the concentration of H+ and OH- ions is approximately 1 x 10^-7 M at 25°C.

The pH and pOH scales are used to quantify the acidity and basicity of solutions. The pH scale ranges from 0 to 14, with values less than 7 indicating acidity, values greater than 7 indicating basicity, and a value of 7 indicating neutrality. The pOH scale also ranges from 0 to 14, but the relationship is reversed: values less than 7 indicate basicity, values greater than 7 indicate acidity, and a value of 7 indicates neutrality.

As we discussed earlier, the sum of pH and pOH is always 14 at 25°C. This relationship is crucial for understanding the interplay between acidity and basicity in aqueous solutions. If we know the pH of a solution, we can easily calculate its pOH, and vice versa.

In the case of our problem, we calculated the pOH to be 1.02. This low pOH value indicates a high concentration of hydroxide ions, which is characteristic of basic solutions. Therefore, we confidently classified the solution as basic.

Understanding the concepts of acidic, basic, and neutral solutions is fundamental to chemistry. It allows us to predict how substances will behave in different environments and how they will react with each other. By mastering these concepts, you'll be well-equipped to tackle more advanced topics in chemistry.

Conclusion

So, guys, we've successfully calculated the pOH of a solution given its hydroxide ion concentration and classified it as basic. We've also discussed the importance of pOH and its relationship to pH and the classification of solutions as acidic, basic, or neutral. Remember, practice makes perfect, so keep working on these types of problems to solidify your understanding. Chemistry can be challenging, but with a solid grasp of the fundamentals, you'll be well on your way to mastering it!

In this article, we addressed the problem of calculating the pOH of a solution and classifying it as acidic, basic, or neutral. We first calculated the pOH using the formula pOH = -log[OH-], obtaining a value of 1.02. Then, we classified the solution as basic based on its low pOH value, indicating a high concentration of hydroxide ions. We also discussed the importance of pOH in chemistry and its relationship to pH and the classification of solutions. This comprehensive explanation should help you better understand acid-base chemistry and tackle similar problems with confidence.