how would you prepare a 500 mL of 0.020M KMnO4 solution?
1.5803
To prepare a 500 mL of 0.020 M KMnO4 (potassium permanganate) solution, you will need the following steps:
1. Calculate the amount of KMnO4 needed:
The molar mass of KMnO4 is 158.04 g/mol.
Molarity (M) is defined as moles of solute per liter of solution.
So, for a 0.020 M solution, you need 0.020 moles of KMnO4 per liter.
Moles = Molarity x Volume (in liters)
Moles = 0.020 M x 0.500 L
Moles = 0.010 mol
Therefore, you will need 0.010 moles of KMnO4.
2. Convert moles to grams:
Mass (g) = Moles x Molar mass
Mass (g) = 0.010 mol x 158.04 g/mol
Mass (g) = 1.58 g
You will need approximately 1.58 grams of KMnO4.
3. Dissolve KMnO4 in water:
Pour 1.58 grams of KMnO4 into a container (such as a beaker).
4. Add distilled water:
Add distilled water to the container while stirring until the total volume reaches 500 mL.
5. Mix well:
Stir the solution until the KMnO4 is completely dissolved.
6. Verify the molarity:
Use a burette or a graduated pipette to transfer a known volume of the solution (e.g., 10 mL) to a flask.
Add a specified reagent to react with KMnO4, and perform a titration to determine the exact concentration (if required).
To prepare a 500 mL of 0.020M KMnO4 solution, you will need to follow these steps:
1. Determine the molar mass of KMnO4.
- The molar mass of KMnO4 is calculated by adding the atomic masses of its constituent elements: K (potassium), Mn (manganese), and O (oxygen). The atomic masses can be found on the periodic table.
2. Convert the desired concentration to moles per liter.
- To convert from molarity (M) to moles per liter (mol/L), divide the desired molarity by 1000 (since there are 1000 mL in a liter).
0.020 M / 1000 = 0.020 mol/L
3. Calculate the number of moles of KMnO4 needed.
- The amount of KMnO4 needed can be determined using the equation:
moles = concentration × volume (in liters)
Moles of KMnO4 = 0.020 mol/L × 0.500 L
Moles of KMnO4 = 0.010 mol
4. Convert moles to grams using the molar mass.
- Multiply the number of moles by the molar mass of KMnO4 to determine the mass needed.
Mass of KMnO4 = 0.010 mol × molar mass of KMnO4
5. Dissolve the mass of KMnO4 in a sufficient volume of water.
- Weigh the calculated mass of KMnO4 using a balance.
- Transfer the KMnO4 to a clean container.
- Add a small amount of water to dissolve the KMnO4 completely.
- Once dissolved, transfer the solution to a 500 mL volumetric flask.
- Add water to the 500 mL mark on the flask to bring the solution volume to 500 mL.
Note: Safety precautions should be taken when handling chemicals.
molarity = # moles/liter of solution.
So how many moles do we want for 500 mL of 0.02 M KMnO4? We want
M x L = moles = 0.02 x 0.5 L = 0.01 moles.
moles = grams/molar mass.
You know moles and molar mass, calculate grams.