Question

Fill in the word acidic, basic, or neutral for the following solutions at \(25^{\circ} \mathrm{C}:\) (a) \(\mathrm{pOH}>7\); solution is _______________ (b) \(\mathrm{pOH}=7 ;\) solution is ______________ (c) \(\mathrm{pOH}<7 ;\) solution is _______________

Short answer

(a) acidic, (b) neutral, (c) basic.

Step-by-step solution

Understanding the Relationship between pH and pOH

First, we need to understand the relationship between \( ext{pH}\) and \( ext{pOH}\). At 25°C, the sum of \( ext{pH}\) and \( ext{pOH}\) is always 14. So, we have: \[ ext{pH} + ext{pOH} = 14.\]

Determine Nature of Solution for pOH > 7

For a pOH greater than 7, \( ext{pH}\) must be less than 7 because \( ext{pH} = 14 - ext{pOH}\). A \( ext{pH}\) less than 7 indicates an acidic solution, so the solution is **acidic**.

Determine Nature of Solution for pOH = 7

When \( ext{pOH} = 7\), the \( ext{pH}\) will also be 7, because \( ext{pH} = 14 - 7 = 7\). A \( ext{pH}\) of 7 indicates a neutral solution, so the solution is **neutral**.

Determine Nature of Solution for pOH < 7

For a pOH less than 7, \( ext{pH}\) must be greater than 7 because \( ext{pH} = 14 - ext{pOH}\). A \( ext{pH}\) greater than 7 indicates a basic solution, so the solution is **basic**.

Key concepts

pH and pOH relationship

The pH and pOH are measures of the acidity and basicity of a solution, respectively. At a temperature of 25°C, there is an important relationship between these two values. The sum of the pH and pOH of a solution is always 14. This is expressed in the equation: \[ \text{pH} + \text{pOH} = 14 \] Understanding this relationship is crucial for determining the nature of a solution. If you know the pOH, you can easily find the pH by subtracting the pOH from 14, and vice versa. This relationship helps to quickly categorize solutions as acidic, neutral, or basic.

acidic solutions

Acidic solutions have a higher concentration of hydrogen ions compared to hydroxide ions. In terms of pH, acidic solutions have a pH value less than 7. But what about pOH? When pOH is greater than 7, it means that the pH is less than 7 due to the equation \( \text{pH} = 14 - \text{pOH} \). This results in a higher concentration of hydrogen ions, indicating an acidic solution. Common examples of acidic solutions include lemon juice and vinegar. Key characteristics of acidic solutions include:- Sour taste- Ability to conduct electricity- Reactivity with metals to produce hydrogen gasUnderstanding these properties can help you identify acidic solutions in everyday life.

neutral solutions

Neutral solutions are a special case where the concentrations of hydrogen ions and hydroxide ions are equal. This balance is reflected in both the pH and pOH being equal to 7. When pOH is 7, the pH is also 7, as calculated by the equation \( \text{pH} = 14 - \text{pOH} \). Water is the most common example of a neutral solution at 25°C. Neutral solutions have distinctive features:- No overall electrical charge- Neither acidic nor basic taste- Generally non-reactive with metalsThese properties make neutral solutions a baseline against which acidic and basic solutions are compared.

basic solutions

Basic solutions, also known as alkaline solutions, have a higher concentration of hydroxide ions than hydrogen ions. The pH of a basic solution is greater than 7. To understand this in terms of pOH, when pOH is less than 7, the corresponding pH will be greater than 7, following from \( \text{pH} = 14 - \text{pOH} \). This results in typical characteristics of basic solutions, such as:- Bitter taste- Slippery feel (like soap) - Capability to turn red litmus paper blueCommon examples of basic solutions are baking soda solution and ammonia. Recognizing these features can help you identify base solutions in various environments.