Preparing a Solution:
A. Calculate the amount of methylene blue chloride (MW = 319.8 g/mol) needed to make 50 ml of a 10 mM stock solution. (Show calculations below)
B. If you wanted to then dilute the solution from Part A to a final concentration of 0.1mM (in 50 ml total volume), what volumes of dye and water would you use? (Show calculations below)
A. To calculate the amount of methylene blue chloride needed to make a 10 mM stock solution in 50 ml, we need to use the equation:
moles of solute = concentration (M) × volume (L)
Given:
Concentration = 10 mM
Volume = 50 ml = 0.05 L (since 1L = 1000 ml)
First, let's convert the concentration from mM to M:
10 mM = 10 × 10^-3 M = 0.01 M
Now, we can calculate the number of moles of methylene blue chloride needed:
moles of solute = 0.01 M × 0.05 L = 0.0005 moles
Next, we need to calculate the mass of methylene blue chloride using its molar mass:
mass (g) = moles × molar mass
mass (g) = 0.0005 moles × 319.8 g/mol = 0.1599 g
Therefore, you would need approximately 0.1599 grams of methylene blue chloride to make a 10 mM stock solution in 50 ml.
B. To dilute the solution from Part A to a final concentration of 0.1 mM in a total volume of 50 ml, we need to use the dilution equation:
C1V1 = C2V2
where:
C1 = initial concentration of the stock solution (10 mM)
V1 = volume of the stock solution used
C2 = final concentration (0.1 mM)
V2 = final volume (50 ml)
Let's solve for V1, the volume of the stock solution used:
V1 = (C2 × V2) / C1
V1 = (0.1 mM × 50 ml) / 10 mM
V1 = 0.5 ml
So, you would need to use 0.5 ml of the stock solution from Part A.
To calculate the volume of water, use the equation:
Volume of water = V2 - V1
Volume of water = 50 ml - 0.5 ml
Volume of water = 49.5 ml
Therefore, you would use 0.5 ml of the dye solution from Part A and dilute it in 49.5 ml of water to obtain a final concentration of 0.1 mM in a total volume of 50 ml.