How many grams of solute would you use to prepare the following solutions? (a) 500.0 mL of 1.25 M NaOH

Verified step by step guidance

1. Determine the molarity equation: Molarity (M) = \( \frac{\text{moles of solute}}{\text{liters of solution}} \)
2. Convert the volume of the solution from milliliters to liters: 500.0 mL = 0.5000 L
3. Use the molarity equation to find the moles of NaOH: \( \text{moles of NaOH} = \text{Molarity} \times \text{Volume in liters} \)
4. Calculate the molar mass of NaOH: Na (22.99 g/mol) + O (16.00 g/mol) + H (1.01 g/mol) = 39.99 g/mol
5. Convert moles of NaOH to grams using the molar mass: \( \text{grams of NaOH} = \text{moles of NaOH} \times \text{molar mass of NaOH} \)

Key Concepts

Molarity (M)

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L). Understanding molarity is crucial for calculating how much solute is needed to achieve a desired concentration in a given volume of solution.

Moles of Solute

A mole is a unit that quantifies the amount of substance. One mole contains approximately 6.022 x 10^23 entities (Avogadro's number). To find the number of moles needed for a solution, you multiply the molarity by the volume of the solution in liters, which is essential for determining how much solute to weigh out.

Mass of Solute

The mass of solute can be calculated using the formula: mass = moles × molar mass. The molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). This concept is vital for converting the calculated number of moles into grams, allowing for the accurate preparation of solutions.