Calculate the pH of solutions prepared by: (a) Dissolving 4.8 g of lithium hydroxide in water to give 250 mL of solution.

Verified step by step guidance

1. Calculate the number of moles of lithium hydroxide (LiOH) using its molar mass.
2. Determine the molarity of the LiOH solution by dividing the number of moles by the volume of the solution in liters.
3. Recognize that LiOH is a strong base and dissociates completely in water, so the concentration of OH⁻ ions is equal to the molarity of the LiOH solution.
4. Calculate the pOH of the solution using the formula \( \text{pOH} = -\log[\text{OH}^-] \).
5. Convert the pOH to pH using the relationship \( \text{pH} + \text{pOH} = 14 \).

Key Concepts

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14. A pH of 7 is neutral, values below 7 indicate acidity, and values above 7 indicate basicity. The scale is logarithmic, meaning each whole number change represents a tenfold change in hydrogen ion concentration.

Strong Bases

Strong bases, like lithium hydroxide (LiOH), completely dissociate in water to produce hydroxide ions (OH-). This complete dissociation means that the concentration of hydroxide ions directly influences the pH of the solution, making it essential to calculate the concentration of LiOH to determine the resulting pH.

Concentration Calculations

To find the pH of a solution, it is crucial to calculate the molarity, which is the number of moles of solute per liter of solution. For lithium hydroxide, the mass of the solute is converted to moles using its molar mass, and then the volume of the solution is used to find the concentration, which is necessary for determining the pH.