You are given a bottle of dry NaCl. Explain the procedures required to make 900mL of a 0.5M NaCl solution. The formula weight of NaCl is 58.4g/mole.
To make a 900mL 0.5M NaCl solution from a bottle of dry NaCl weighing 58.4g/mole, you need to follow these steps:
1. Calculate the amount of NaCl needed:
- First, determine the molar mass of NaCl, which is 58.4g/mole.
- Since you want a 0.5M solution, you need to find the moles of NaCl required.
- The formula for calculating moles is: Moles = Mass / Molar Mass.
- In this case, the mass is the desired volume (900mL) multiplied by the desired molarity (0.5M).
- Convert the volume to liters by dividing it by 1000 (900mL = 0.9L).
- The equation becomes: Moles = Volume (L) * Molarity.
- Calculate: Moles = 0.9L * 0.5M = 0.45 moles of NaCl.
2. Weigh out the required amount of NaCl:
- You know that the molar mass of NaCl is 58.4g/mole, and you have calculated the moles needed as 0.45 moles.
- Multiply the moles by the molar mass to find the required mass: Mass = Moles * Molar Mass.
- Calculate: Mass = 0.45 moles * 58.4g/mole = 26.28 grams.
3. Dissolve the weighed NaCl in water:
- Take your accurately measured 26.28 grams of NaCl and add it to a container, preferably a beaker.
- Add a small volume (about 100-200 mL) of distilled water to the container.
- Stir the mixture well until the solid NaCl dissolves completely.
4. Adjust the volume to make a 900mL solution:
- Once the NaCl is dissolved, carefully transfer the solution to a 900mL volumetric flask using a funnel.
- Rinse the container to ensure all the NaCl solution is transferred.
- Add distilled water to the volumetric flask until the mark on the neck of the flask is reached.
- Cap the flask and mix the solution by inverting it several times.
Congratulations! You have successfully prepared a 900mL 0.5M NaCl solution. Remember to label the container appropriately to indicate the concentration and contents.