Introduction
If you have a solution with a known molarity, you can use this known solution to make a new solution by
adding water. Adding more water (the solvent) to the solution is called dilution. The solution becomes
“watered down” or diluted. Adding water does not change the total number of solute particles in
solution. However, adding water does change the ratio of solute particles to solvent particles. Diluting
the solution causes the new solution to have a lower concentration.
Diluted solutions are related to the original concentrated solutions according to the following equation:
Procedure
Part A: Make a MgSO4 stock solution
1. Measure mass of solute (salt). Tare an empty weigh boat. Using a scoopula, transfer about 33 g
of MgSO4 (aka Epsom Salt) into the weigh boat. Record the actual mass shown on the balance
(Mass of solid salt (g)).
2. Carefully, transfer all of the salt from the weigh boat into the volumetric flask. To reduce
transfer loss errors, add a small amount of water to the weigh boat, swirl and pour the water
into the volumetric flask.
3. Add enough DI water to the flask to fill the bulb about three-quarters (3/4) full. Swirl to start
dissolving the salt. You may also want to place your thumb over the flask opening and invert the
flask several times to facilitate mixing.
4. When the salt is mostly dissolved, add water until the bottom of the meniscus is about 1/2 inch
from the calibration line on the neck. Mix again.
5. When the salt is completely dissolved, add water to raise the bottom of the meniscus to the