Problem 98 - Introductory Chemistry Atoms First

Question

Define molarity.

Step-by-Step Solution

Answer

Molarity is a measure of the concentration of a solute in a solution, expressed in moles of solute per liter of solution (mol/L), and denoted by the letter M. The formula for calculating molarity is \(M = \frac{n}{V}\), where \(M\) is the molarity, \(n\) is the number of moles of solute, and \(V\) is the volume of the solution in liters. It is a crucial concept in chemistry for comparing concentrations of different solutions and performing calculations involving chemical reactions.

Step 1: Definition of Molarity

Molarity is a measure of the concentration of a solute in a solution, expressed as the number of moles of solute per liter of solution (mol/L). It is often denoted by the letter M. This allows us to easily compare the concentrations of different solutions and perform calculations involving chemical reactions.

Step 2: Formula for Calculating Molarity

The formula for calculating molarity (M) is given by the following equation: \[M = \frac{n}{V}\] where: - \(M\) is the molarity (mol/L) - \(n\) is the number of moles of solute (mol) - \(V\) is the volume of the solution (L)

Step 3: Understanding Molarity

To better understand molarity, let's consider an example. Suppose we have 1 mole of sodium chloride (NaCl) dissolved in 1 liter of water. The molarity of this sodium chloride solution would be: \[M = \frac{1 \, \text{mol of NaCl}}{1 \, \text{L of solution}}\] Therefore, the molarity of this solution is 1 mol/L, or simply 1 M.

Step 4: Using Molarity in Calculations

Molarity can be used in various calculations involving chemical reactions. For example, in a titration experiment, the molarity and volume of one reactant can be used to determine the molarity of another reactant: \[M_1V_1 = M_2V_2\] where: - \(M_1\) and \(M_2\) are the molarities of the two reactants - \(V_1\) and \(V_2\) are the volumes of the respective reactants In summary, molarity is a crucial concept in chemistry that helps us define the concentration of a solution and enables us to perform calculations involving chemical reactions.