Describe how you would prepare each of the following aqueous solutions, starting with solid KBr: (b) 125 g of 0.180 m KBr,

Key Concepts

Molarity

Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. It is crucial for preparing solutions, as it allows chemists to quantify how much solute is needed to achieve a desired concentration. In this case, a 0.180 M solution of KBr means that there are 0.180 moles of KBr in every liter of the solution.

Moles and Molar Mass

To prepare a solution, it is essential to understand the relationship between moles and molar mass. The molar mass of KBr is approximately 119.0 g/mol, which means that one mole of KBr weighs 119.0 grams. To find out how many grams are needed for a specific molarity, you can use the formula: grams = moles × molar mass.

Dilution and Solution Preparation

Preparing a solution involves dissolving a specific amount of solute in a solvent, typically water, to achieve the desired concentration. For the given problem, you would first calculate the number of moles required for 125 g of a 0.180 M KBr solution, then weigh out the appropriate mass of KBr, and finally dissolve it in enough water to reach the total volume of the solution, ensuring thorough mixing.