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0.2 m naoh ph

Understanding the pH of 0.2% Sodium Hydroxide (NaOH) Solutions

Sodium hydroxide (NaOH), commonly known as caustic soda or lye, is a highly versatile chemical widely used in various industries, including manufacturing, food processing, and laboratory applications. One of the most important characteristics of NaOH is its strong alkaline nature, which directly affects the pH of its solutions. In this article, we will explore the pH of a 0.2% sodium hydroxide solution and its implications in different contexts.

When we refer to a 0.2% sodium hydroxide solution, we mean that there are 0.2 grams of NaOH dissolved in 100 milliliters of water. Sodium hydroxide is a strong base that fully dissociates in water, meaning it releases hydroxide ions (OH-) when dissolved. The dissociation can be represented by the equation

\[ \text{NaOH} \rightarrow \text{Na}^+ + \text{OH}^- \]

Due to the complete dissociation of NaOH, even a relatively low concentration like 0.2% leads to a significant increase in the hydroxide ion concentration in the solution. In this case, the concentration of hydroxide ions can be calculated using the formula

\[ \text{[OH}^-] = \frac{\text{moles of NaOH}}{\text{volume of solution in liters}} \]

For a 0.2% solution, the molarity can be calculated using the molecular weight of NaOH, which is approximately 40 grams per mole. Therefore, a 0.2% solution equates to about 0.05 moles of NaOH in 1 liter of water.

Substituting the values, we find that the concentration of hydroxide ions in a 0.2% NaOH solution is approximately 0.05 moles of OH- per liter. To find the pH, we first need to calculate the pOH using the formula

0.2 m naoh ph

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

Upon calculation, the pOH of a 0.2% NaOH solution is found to be approximately 1.3. Since pH and pOH are related through the equation

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

we can easily compute the pH of the solution

\[ \text{pH} = 14 - \text{pOH} = 14 - 1.3 = 12.7 \]

This pH value of 12.7 indicates that the solution is highly alkaline. Such alkaline solutions can be corrosive, and safety precautions should always be taken when handling them. In laboratory settings, NaOH solutions are often used for titrations, neutralization reactions, and as a cleaning agent.

In summary, a 0.2% sodium hydroxide solution has a pH of approximately 12.7, reflecting its strong basic nature. Understanding the pH of NaOH solutions is essential in both industrial applications and laboratory experiments, ensuring safety and proper handling of this powerful chemical. Always remember to wear appropriate personal protective equipment when working with strong bases like sodium hydroxide to mitigate any risks associated with its use.

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