nov. . 14, 2024 14:42 Back to list

0.05 m naoh ph

Understanding the pH of 0.05% NaOH Solution

Sodium hydroxide (NaOH), commonly known as lye or caustic soda, is a highly versatile chemical widely used in various industries, including manufacturing, food processing, and water treatment. When dissolved in water, sodium hydroxide dissociates into sodium ions (Na⁺) and hydroxide ions (OH⁻), resulting in an alkaline solution. One of the critical parameters for any solution is its pH level, which indicates the acidity or alkalinity of the solution.

To fully understand the pH of a 0.05% NaOH solution, we first need to comprehend how pH is defined. The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 indicate acidic solutions, while values above 7 indicate alkaline solutions. Each whole number change on the pH scale represents a tenfold change in hydrogen ion concentration. Therefore, a solution with a pH of 10 is ten times less acidic than one with a pH of 9.

Calculating the pH of a sodium hydroxide solution requires knowing its concentration in moles per liter (molarity). A 0.05% (w/v) NaOH solution translates into 0.05 grams of NaOH per 100 milliliters of solution. To convert this into molarity, we must determine the molar mass of NaOH, which is approximately 40 g/mol.

To find the molarity (M), we utilize the formula

\[ \text{Molarity} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)} \times \text{volume (L)}} \]

For 0.05 grams of NaOH in 100 mL of water (0.1 L), the calculation becomes

\[ \text{Molarity} = \frac{0.05 \text{ g}}{40 \text{ g/mol} \times 0.1 \text{ L}} = \frac{0.05}{4} = 0.0125 \text{ M} \]

Now that we have the molarity of the NaOH solution, we can find the pOH of the solution. The hydroxide ion concentration \([OH^-]\) can be directly determined from the molarity of the NaOH, as each NaOH molecule produces one hydroxide ion. Therefore, the concentration of hydroxide ions in our solution is also 0.0125 M.

Next, we can calculate the pOH using the formula

0.05 m naoh ph

\[ \text{pOH} = -\log[OH^-] \]

Substituting in our value

\[ \text{pOH} = -\log(0.0125) \approx 1.90 \]

Since pH and pOH are related through the equation

\[ \text{pH} + \text{pOH} = 14 \]

We can now find the pH of the 0.05% NaOH solution

\[ \text{pH} = 14 - \text{pOH} = 14 - 1.90 = 12.10 \]

This indicates that a 0.05% NaOH solution is quite alkaline, with a pH of approximately 12.10. Such a high pH reflects the strong basic nature of sodium hydroxide, which can cause saponification in the presence of fats, corrosion of certain metals, and a variety of other chemical reactions.

It is important to handle NaOH solutions with care. Exposure can lead to severe skin and eye irritation, and improper disposal can result in environmental hazards. Understanding the properties of NaOH, including its pH, is essential for safe and effective usage in industrial and laboratory settings.

In conclusion, the pH of a 0.05% NaOH solution is approximately 12.10. This value illustrates the strong alkaline nature of sodium hydroxide and its potential applications, as well as the necessary precautions that must be taken when working with such substances. Whether used for cleaning, food production, or chemical synthesis, knowledge of pH plays a crucial role in leveraging the properties of sodium hydroxide responsibly and effectively.

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