Molarity Calculation for Sodium Hydroxide Solutions

Molarity is a crucial concept in chemistry that allows us to express the concentration of a solution in terms of the number of moles of solute per liter of solution. In this article, we will explore how to calculate molarity for different scenarios involving sodium hydroxide (NaOH) solutions.

How to Calculate Molarity

Molarity (M) is defined as the number of moles of solute per liter of solution (m3)

The formula to calculate molarity is:

M frac{text{moles of solute}}{text{volume of solution in liters}}

Example 1: 30 grams of NaOH in 500 milliliters of solution

To find the molarity for this case, we follow these steps:

Determine the molar mass of NaOH: Molar mass of NaOH 23 (Na) 16 (O) 1 (H) 40 g/mol. Calculate the moles of NaOH: n frac{30 text{ g}}{40 text{ g/mol}} 0.75 text{ mol} Convert milliliters to liters: 500 mL 0.5 L. Calculate molarity: M frac{0.75 text{ mol}}{0.5 text{ L}} 1.5 text{ M}

Therefore, the molarity of the NaOH solution is 1.5 M.

Example 2: 60 grams of NaOH in 500 milliliters of solution

Here is another example for clarity:

Determine the molar mass of NaOH: Molar mass of NaOH 23 (Na) 16 (O) 1 (H) 40 g/mol. Calculate the moles of NaOH: n frac{60 text{ g}}{40 text{ g/mol}} 1.5 text{ mol} Convert milliliters to liters: 500 mL 0.5 L. Calculate molarity: M frac{1.5 text{ mol}}{0.5 text{ L}} 3 text{ M}

Therefore, the molarity of the NaOH solution is 3 M.

Summary of Key Points

Molarity (M) is the number of moles of solute per liter of solution. Molar mass (M) of NaOH 40 g/mol. To calculate molarity, the volume of the solution must be in liters. The solvent is often water, as in most common solutions involving NaOH.

Additional Considerations

When dealing with different volumes, it is important to adjust the calculations accordingly. For instance, if you have 60 grams of NaOH in 500 milliliters, you would first calculate the moles, then adjust for the volume to find the molarity.

Conclusion

In summary, molarity is a fundamental concept in chemistry, and understanding how to calculate it is essential for solving various problems related to solution concentration. The examples provided in this article should help you to apply the molarity formula effectively in different scenarios.