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2 m naoh ph

Understanding the pH of 2% NaOH Solution

Sodium hydroxide (NaOH), commonly known as lye or caustic soda, is a highly soluble ionic compound that plays a pivotal role in various industrial and laboratory applications. When we prepare a 2% (w/v) sodium hydroxide solution, it is essential to understand its pH, as this property influences its use in different chemical processes and reactions.

To begin with, a 2% NaOH solution indicates that there are 2 grams of NaOH dissolved in 100 mL of water. Sodium hydroxide is a strong base, which means it completely dissociates in water into its constituent ions sodium ions (Na⁺) and hydroxide ions (OH⁻). This dissociation is a key characteristic of strong bases, as they increase the concentration of hydroxide ions in the solution significantly.

The pH scale, ranging from 0 to 14, is a measure of hydrogen ion concentration in a solution. In the context of a basic solution, the pH value is above 7. Pure water is neutral with a pH of 7, while solutions with pH values less than 7 are acidic. Given that NaOH is a strong base, the pH of a 2% solution is expected to be substantially higher than 7.

To approximate the pH of a 2% NaOH solution, we first need to calculate its molarity. The molar mass of NaOH is approximately 40 g/mol. Thus, a 2% solution contains 2 g of NaOH per 100 mL. This translates to a molarity (M) of

\[ \text{Molarity} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)} \times \text{volume (L)}} = \frac{2 \, \text{g}}{40 \, \text{g/mol} \times 0.1 \, \text{L}} = 0.5 \, \text{M} \]

Since 0.5 M NaOH dissociates completely in solution, the concentration of OH⁻ ions is also 0.5 M. To calculate the pOH, we use the formula

2 m naoh ph

\[ \text{pOH} = -\log[OH⁻] = -\log(0.5) \approx 0.3 \]

Next, we can find the pH using the relationship

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

Substituting the calculated pOH

\[ \text{pH} = 14 - 0.3 = 13.7 \]

Therefore, the pH of a 2% NaOH solution is approximately 13.7, indicating that it is highly alkaline. This elevated pH level underscores the utility of sodium hydroxide in various applications, such as cleaning agents, pH adjustment, and chemical synthesis.

In conclusion, understanding the pH of a 2% NaOH solution is crucial for its effective application in many fields. The high pH value of approximately 13.7 reflects its strong basic nature, making it a valuable reagent in chemical and industrial processes.

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