How to Prepare Molar Salt Solutions: A Step-by-Step Guide

Preparing molar solutions is an essential skill in chemistry, allowing for accurate and precise measurements in experiments and research. Sodium chloride (NaCl) is a common salt used in many applications. This guide will walk you through the process of preparing a 1 molar 200 mL solution of NaCl, along with the calculations involved.

Understanding Molarity

Molarity (M) is a measure of concentration defined as the number of moles of solute per liter of solution. The formula for calculating molarity is:

M n / V

where n is the number of moles of solute and V is the volume of the solution in liters.

The molar mass of NaCl (sodium chloride) is calculated by adding the atomic masses of sodium (Na) and chlorine (Cl):

Na: 23 g/mol Cl: 35.5 g/mol Molar mass of NaCl 23 g/mol 35.5 g/mol 58.5 g/mol

Preparation of 1 Molar 200 mL NaCl Solution

The goal is to prepare a 1 molar 200 mL (0.2 L) solution of NaCl. Here are the steps and calculations involved:

Step 1: Calculate the Amount of NaCl Required

We know that 1 mole of NaCl is 58.5 g in 1 liter of solution. To determine the amount of NaCl needed for 0.2 L (200 mL) of solution:

grams of NaCl (molar mass of NaCl × volume of solution in liters)

grams of NaCl (58.5 g × 0.2 L)

grams of NaCl 11.7 g

Step 2: Verify the Calculation

To verify, let's go through the original methods mentioned in the provided content:

Method 1: A 10 g of NaCl in 1 L solution needs to be multiplied by 5 to achieve a 5 molar solution. For a 5 molar solution in 1 L, the amount is 58.44 g (58.5 g rounded to 2 decimal places). Method 2: For a 5 molar solution in 1 L, 11.7 g of NaCl is required. To find the amount needed for 200 mL of 5 molar solution, use the calculation:

grams of NaCl (11.7 g × 200 mL / 1000 mL)

grams of NaCl 2.34 g * 5 11.7 g

Conclusion

By following these steps and calculations, you can accurately prepare a 1 molar 200 mL NaCl solution. The key is understanding the concept of molarity and using the molar mass of NaCl to calculate the appropriate amount of solute needed for the desired concentration.

Related Keywords

- molar solution - NaCl - molarity calculation

References

For more in-depth information on molarity and solutions, refer to standard chemistry textbooks or online resources such as Khan Academy.