how to prepare a 250 mL solution of .15 M K2SO4 with a volumetric flask
How many moles K2SO4 do you need? That's M x L = ?
0.15 x 0.250 = 0.0375. Convert to grams.
mols = grams/molar mass and g = mols x molar mass = you do it.
Take that many grams K2SO4, place in a 250 mL volumetric flask, add some distilled or deionized water, swirl until all of the solid is dissolved, make to the mark on the volumetric flask with deionized water, stopper, mix thoroughly, label.
To prepare a 250 mL solution of 0.15 M K2SO4 using a volumetric flask, you will need a few basic steps. Here is a step-by-step guide:
1. Calculate the amount of K2SO4 needed:
- Molarity (M) is defined as moles of solute per liter of solution. In this case, the desired molarity is 0.15 M.
- Convert the desired molarity to moles per liter: 0.15 moles/L.
- Multiply the molarity by the volume in liters: 0.15 moles/L * 0.25 L = 0.0375 moles.
- Since K2SO4 has a molar mass of approximately 174.26 g/mol, the required mass can be calculated by multiplying the moles by the molar mass: 0.0375 moles * 174.26 g/mol = 6.5695 grams.
2. Weigh out the calculated amount of K2SO4 using an analytical balance.
3. Add the weighed K2SO4 to the volumetric flask:
- Use a funnel to pour the K2SO4 into the flask.
- Ensure that all of the solid is transferred into the flask.
4. Add some distilled water to dissolve the K2SO4:
- Use a wash bottle or dropper to add enough distilled water to partially dissolve the solid.
- Swirl the flask gently to facilitate dissolution.
5. Fill the volumetric flask to the final volume:
- Continue adding distilled water to the flask until the bottom of the meniscus is exactly at the calibration mark on the neck of the flask.
- Adjust the final volume carefully, as even a small amount of additional water can significantly affect the concentration.
6. Cap the flask and thoroughly mix the solution:
- Ensure the cap is tightly secured, and then invert the flask several times to mix the solution completely.
Congratulations! You have now prepared a 250 mL solution of 0.15 M K2SO4 using a volumetric flask. Remember to label the flask with the details of the solution for future reference.