How to prepare 0.2M of NaOH in 250ml volumetric flask???
determine the mass of NaOH:
mass=Molarity*molmass*volume
= .2*40*.250
so drop that mass of sodum hydroxide into a flask, slowly fill with water to 250ml, while stiring.
To prepare a 0.2M sodium hydroxide (NaOH) solution in a 250ml volumetric flask, you need to follow these steps:
1. Calculate the amount of NaOH needed:
The molarity (M) is defined as the number of moles of solute per liter of solution. Since you want a 0.2M solution, this means you need 0.2 moles of NaOH per liter of solution.
The formula to calculate the amount of solute needed is:
Amount of solute (in moles) = Molarity (in M) × Volume of solution (in L)
So, in this case, the amount of NaOH needed is:
Amount of NaOH = 0.2M × 0.25L (since the volumetric flask has a volume of 250ml, which is equivalent to 0.25L)
Amount of NaOH = 0.05 moles
2. Calculate the mass of NaOH needed:
To calculate the mass of NaOH, you need to know the molar mass of NaOH, which is 40.01 g/mol.
The formula to calculate the mass of solute needed is:
Mass of solute (in g) = Amount of solute (in moles) × Molar mass (in g/mol)
So, in this case, the mass of NaOH needed is:
Mass of NaOH = 0.05 moles × 40.01 g/mol (molar mass of NaOH)
Mass of NaOH = 2.0 g
3. Weigh out 2.0 grams of NaOH:
Using an analytical balance, carefully weigh out 2.0 grams of NaOH. Handle NaOH with caution as it is a strong base and can cause burns.
4. Dissolve NaOH in water:
Add the weighed NaOH to a beaker containing approximately 100-150mL of distilled water. Stir gently until the NaOH is completely dissolved.
5. Transfer the solution to a 250ml volumetric flask:
Once the NaOH is completely dissolved, carefully transfer the solution into a 250ml volumetric flask. Use a funnel to avoid spilling the solution.
6. Rinse the beaker with distilled water:
Rinse the beaker with distilled water to ensure all the solution is transferred to the volumetric flask, and pour this rinse solution into the flask.
7. Fill the volumetric flask to the mark:
Slowly add distilled water to the flask, swirling gently as you approach the mark on the neck of the flask. Once the bottom of the meniscus touches the mark, the flask contains 250ml of solution.
8. Mix well:
Cap the flask and mix the solution thoroughly by inverting it several times or using a glass rod, ensuring the solution is homogeneously mixed.
Now, you have prepared a 0.2M NaOH solution in a 250ml volumetric flask. Remember to label the flask properly with the concentration and date of preparation.