How many grams of SrO should be dissolved in sufficient water to make 2.00 L of a solution with a pH of 10.0?

Verified step by step guidance

Step 1: Understand that the pH of the solution is 10.0, which means the pOH is 14.0 - 10.0 = 4.0. Use the relationship between pOH and hydroxide ion concentration: \( \text{pOH} = -\log[\text{OH}^-] \) to find \([\text{OH}^-]\).

Step 2: Calculate the hydroxide ion concentration \([\text{OH}^-]\) using the formula \([\text{OH}^-] = 10^{-\text{pOH}}\). Substitute the pOH value to find \([\text{OH}^-]\).

Step 3: Recognize that SrO is a strong base and dissociates completely in water to form Sr²⁺ and 2 OH⁻ ions. Therefore, the concentration of SrO needed is half the concentration of \([\text{OH}^-]\) because each mole of SrO produces two moles of OH⁻.

Step 4: Calculate the moles of SrO required using the formula \( \text{moles of SrO} = \frac{[\text{OH}^-]}{2} \times \text{Volume of solution in liters} \).

Step 5: Convert the moles of SrO to grams using the molar mass of SrO. Use the formula \( \text{mass of SrO} = \text{moles of SrO} \times \text{molar mass of SrO} \).

Key Concepts

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

pH and pOH

pH is a measure of the acidity or basicity of a solution, defined as the negative logarithm of the hydrogen ion concentration. A pH of 10.0 indicates a basic solution, where the concentration of hydroxide ions (OH-) is higher than that of hydrogen ions (H+). The relationship between pH and pOH is given by the equation pH + pOH = 14, allowing us to calculate the pOH and subsequently the concentration of hydroxide ions in the solution.

Dissociation of SrO

Strontium oxide (SrO) is a basic oxide that reacts with water to form strontium hydroxide (Sr(OH)2). This dissociation increases the concentration of hydroxide ions in the solution, contributing to the basicity. Understanding this reaction is crucial for determining how much SrO is needed to achieve the desired pH level in the solution.

Molarity and Solution Preparation

Molarity (M) is a way to express the concentration of a solution, defined as the number of moles of solute per liter of solution. To prepare a solution with a specific pH, one must calculate the required molarity of hydroxide ions and then convert this to the mass of SrO needed using its molar mass. This involves understanding the relationship between moles, mass, and volume in solution preparation.

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