What is the molarity of 6 moles $(mol)$ of NaCl dissolved in 2 L of water?
A. $\frac{6 mol}{2 L}$
B. $\frac{6 L}{2 mol}$
C. $\frac{2 L}{6 mol}$
D. $\frac{2 mol}{6 L}$
Answer (1)
Molarity is defined as moles of solute per liter of solution.
Calculate molarity using the formula: Molarity = liters of solution moles of solute .
Substitute the given values: Molarity = 2 L 6 moles .
Simplify to find the molarity: 3 mol/L .
Explanation
Understanding the Problem We are given 6 moles of NaCl dissolved in 2 L of water and asked to find the molarity of the solution. Molarity is defined as the number of moles of solute per liter of solution.
Setting up the Calculation Molarity is calculated by dividing the number of moles of solute by the volume of the solution in liters. In this case, the solute is NaCl, and we have 6 moles of it. The volume of the solution is 2 L.
Calculating Molarity To find the molarity, we perform the division: Molarity = 2 L 6 moles = 3 mol/L
Final Answer Therefore, the molarity of the NaCl solution is 3 mol/L. This corresponds to option A, which represents the correct calculation setup.
Examples
Molarity is a crucial concept in chemistry, especially when preparing solutions for experiments. For example, if you need to create a saline solution with a specific concentration for a biology experiment, you would use molarity to calculate the exact amount of salt (solute) to dissolve in a given volume of water (solvent). Suppose you need 0.5 L of a 1 mol/L NaCl solution. Using the molarity formula, you would determine that you need 0.5 moles of NaCl (1 mol/L * 0.5 L = 0.5 moles). Knowing the molar mass of NaCl (approximately 58.44 g/mol), you would then weigh out 29.22 grams of NaCl (0.5 moles * 58.44 g/mol = 29.22 grams) and dissolve it in enough water to make 0.5 L of solution. This ensures your solution has the precise concentration needed for your experiment.
