Calculate the pH of solutions prepared by: (a) Dissolving 0.20 g of sodium oxide in water to give 100.0 mL of solution.

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Convert the mass of sodium oxide (Na2O) to moles using its molar mass. The molar mass of Na2O is approximately 61.98 g/mol.

Calculate the concentration of Na2O in the solution by dividing the number of moles by the volume of the solution in liters (0.100 L).

Recognize that Na2O is a basic oxide and reacts with water to form sodium hydroxide (NaOH). The balanced chemical equation is: Na2O + H2O → 2 NaOH.

Determine the concentration of NaOH produced in the solution. Since 1 mole of Na2O produces 2 moles of NaOH, multiply the concentration of Na2O by 2 to find the concentration of NaOH.

Calculate the pH of the solution. First, find the pOH by taking the negative logarithm (base 10) of the hydroxide ion concentration. Then, use the relation pH + pOH = 14 to find the pH.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is neutral, below 7 indicates acidity, and above 7 indicates basicity. The pH is calculated as the negative logarithm of the hydrogen ion concentration in the solution, which is crucial for understanding the behavior of acids and bases.

Sodium Oxide and Hydrolysis

Sodium oxide (Na2O) is a basic oxide that reacts with water to form sodium hydroxide (NaOH), a strong base. This reaction increases the concentration of hydroxide ions (OH-) in the solution, which directly affects the pH. Understanding this hydrolysis process is essential for calculating the resulting pH of the solution.

Concentration Calculations

To calculate the pH of a solution, it is important to determine the concentration of hydroxide ions produced from the dissolved sodium oxide. This involves converting the mass of sodium oxide into moles and then calculating the molarity based on the final volume of the solution. Accurate concentration calculations are fundamental for determining the pH.

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