Final answer:
To calculate molarity, divide the number of moles of solute by the volume of the solution in liters; convert mass to moles using molecular weight if necessary. Report the answer with the correct number of significant digits.
Step-by-step explanation:
To calculate the molarity of a solution, you need to know the number of moles of solute and the volume of the solution in liters. The molarity (M) is calculated by dividing the moles of solute by the volume of solution in liters (M = moles/L). If you are given the mass of the solute, you first convert the mass to moles using the molecular weight (step b). If necessary, you also convert the solution volume from milliliters to liters (step c).
For example, to find the molarity of a solution containing 42.8 grams of KBr in 1.00 L of water, you calculate the number of moles using the molar mass of KBr (119 g/mole). Dividing the number of moles by the volume in liters gives you the molarity. Hence, Option c 'Divide the moles by the volume in liters' is the correct approach to calculate molarity. As a reminder, the answer should be reported with the correct number of significant digits based on the given figures and measurements.