# What Is the [Oh-] of a Solution Whose PH = 5.43 ?

What Is the [OH-] of a Solution Whose pH = 5.43?

When we talk about the pH of a solution, we are referring to its acidity or alkalinity. It is a measure of the concentration of hydrogen ions (H+) in a solution, with lower pH values indicating higher acidity. However, the hydroxide ion (OH-) is also essential in determining the overall pH of a solution. By understanding the relationship between pH and [OH-], we can determine the [OH-] of a solution when given its pH value.

The pH scale ranges from 0 to 14, with 7 being considered neutral. A pH below 7 indicates acidity, while a pH above 7 indicates alkalinity. The pH value is calculated using the equation:

pH = -log[H+]

Here, [H+] represents the concentration of hydrogen ions in moles per liter. To find the [OH-] concentration, we need to consider the relationship between [H+] and [OH-], which is defined by the equation:

[H+][OH-] = 1.0 x 10^-14

This equation demonstrates that in any aqueous solution, the product of [H+] and [OH-] is constant. Therefore, if we know the [OH-] concentration, we can calculate the [H+] concentration and vice versa.

To determine the [OH-] concentration from a given pH value, we can use the following steps:

Step 1: Calculate [H+] concentration
Using the equation pH = -log[H+], we can rearrange it to find [H+]:

[H+] = 10^(-pH)

Step 2: Calculate [OH-] concentration
Using the equation [H+][OH-] = 1.0 x 10^-14, we can rearrange it to find [OH-]:

[OH-] = 1.0 x 10^-14 / [H+]

Now, let’s apply these steps to find the [OH-] concentration of a solution with pH = 5.43:

Step 1: Calculate [H+] concentration
[H+] = 10^(-5.43)
[H+] = 2.74 x 10^(-6) M

Step 2: Calculate [OH-] concentration
[OH-] = 1.0 x 10^-14 / (2.74 x 10^(-6))
[OH-] = 3.65 x 10^(-9) M

Therefore, the [OH-] concentration of a solution with pH = 5.43 is approximately 3.65 x 10^(-9) M.

FAQs:

Q: Why is the [OH-] concentration important?
A: The [OH-] concentration is crucial for determining the overall pH and acidity of a solution. It helps understand the basicity or alkalinity of a solution and is used in various chemical calculations and reactions.

Q: How does the [OH-] concentration affect the pH?
A: As mentioned earlier, the [OH-] concentration and [H+] concentration are inversely related. If the [OH-] concentration increases, the [H+] concentration decreases, resulting in a higher pH value and a more alkaline solution.

Q: Can the [OH-] concentration ever exceed the [H+] concentration?
A: In neutral solutions, the [OH-] concentration is equal to the [H+] concentration, which is 1.0 x 10^(-7) M. However, in basic or alkaline solutions, the [OH-] concentration exceeds the [H+] concentration.

Q: How can the [OH-] concentration be measured experimentally?
A: The [OH-] concentration can be determined by measuring the concentration of a strong base, such as sodium hydroxide (NaOH), that dissociates completely to produce hydroxide ions.

Q: Is the [OH-] concentration affected by temperature?
A: Yes, temperature impacts the [OH-] concentration. Generally, as temperature increases, the [OH-] concentration also increases. However, this relationship is not linear and varies depending on the specific chemical reaction or equilibrium involved.

In conclusion, the [OH-] concentration of a solution can be determined from its pH value using the relationship between [H+] and [OH-]. By understanding this relationship, we can gain insights into the acidity or alkalinity of a solution and its chemical behavior.