Suppose you have 0.500 M sucrose
stock solution. How do you prepare 250
mL of 0.348 M sucrose solution ?
you need to add water to x mL of stock sucrose so that
.5(x) = .348(.250)
x = .174
so, add 76mL of water to 174mL of .5M sucrose to get 250mL of .348M solution
check:
.5*.174 = .087
.348*.250 = .087
Technically, and this may be a very small point, but I disagree because it assumes that volumes are additive. While that may be true in a few instances it is not true universally, and not very often. In addition I think it is bad practice to leave students with that impression. A better answer, I think, is to take 174 mL of the stock solution AND ADD WATER TO MAKE A TOTAL VOLUME of 250 mL.
The reason I say that is that many a student of mine wanted to say they could add a mole of AgNO3 to 1000 mL water and it makes a 1 M solution. It does not BECAUSE the total volume will be greater than 1000 mL. If the density of water is 1.00 g/mL it will be a 1 m solution but not a 1 M solution. OK, I'm off my soap box. :-)
To prepare a 250 mL sucrose solution with a concentration of 0.348 M using a 0.500 M stock solution, you will need to perform the following steps:
Step 1: Determine the volume of stock solution needed:
The formula for calculating the volume of stock solution is:
(Volume of stock solution) * (Concentration of stock solution) = (Volume of final solution) * (Concentration of final solution)
Let's say the volume of the stock solution needed is V1.
0.500 M * V1 = 0.348 M * 250 mL
Solving for V1:
V1 = (0.348 M * 250 mL) / 0.500 M
V1 = 174 mL
So you will need 174 mL of the 0.500 M stock solution.
Step 2: Determine the volume of solvent (water) needed:
To make a total volume of 250 mL, subtract the volume of the stock solution from the final volume:
Volume of solvent = 250 mL - 174 mL
Volume of solvent = 76 mL
So, you will need 76 mL of solvent (water).
Step 3: Combine the stock solution and solvent:
In a container, pour 174 mL of the 0.500 M stock solution. Then, add 76 mL of solvent (water) to reach a total volume of 250 mL.
Step 4: Mix thoroughly:
Mix the solution thoroughly to ensure a homogeneous sucrose concentration.
After following these steps, you will have prepared 250 mL of 0.348 M sucrose solution using the 0.500 M stock solution.
To prepare a 250 mL of 0.348 M sucrose solution from a 0.500 M sucrose stock solution, you will need to perform a dilution.
Here's how you can do it:
1. Start by calculating the amount of solute (sucrose) needed for the desired concentration, using the equation: M1V1 = M2V2, where M1 is the initial concentration, V1 is the initial volume, M2 is the desired concentration, and V2 is the desired volume.
Let's plug in the values:
M1 = 0.500 M (initial concentration of the stock solution)
V1 = ? (initial volume of the stock solution, which is what we're trying to find)
M2 = 0.348 M (desired concentration of the final solution)
V2 = 250 mL (desired volume of the final solution)
Rearranging the equation, we get:
V1 = (M2 * V2) / M1
Plugging in the values, we get:
V1 = (0.348 M * 250 mL) / 0.500 M
V1 = 174 mL
Therefore, you will need 174 mL of the stock solution.
2. Once you have calculated the volume needed for the stock solution, measure out 174 mL of the 0.500 M sucrose solution using a graduated cylinder or pipette.
3. Transfer the 174 mL of the stock solution to a volumetric flask.
4. Add distilled water to the volumetric flask to bring the total volume up to 250 mL. Use a funnel and be careful not to overfill.
5. Mix the solution thoroughly by swirling the flask gently. Be sure that the sucrose is dissolved completely.
Now you have successfully prepared 250 mL of a 0.348 M sucrose solution from the 0.500 M sucrose stock solution through dilution.