do at home for next week Calculate how to make 10 ml of a 7.5% methylene blue st
ID: 477741 • Letter: D
Question
do at home for next week Calculate how to make 10 ml of a 7.5% methylene blue stock solution (from solid powder) Calculate how to make a series of 1:10 dilutions of this stock. Imagine you'lluse 5 ml of each dilution for your experiment. Calculate the final concentrations of each tube tube 1: take some stock, dilute it 1:10 with some water in a new tube = #1 tube 2: take some of 1, dilute it 1:10 with some water in a new tube tube 3: take some of N2, dilute it 1:10 with some water in a new tube tube 4: take some of 3, dilute it 1:10 with some water in a new tube First, decide the total volume to make of each tube-keep in mind measurement accuracy (consider preparing 20% more solution than what you will use). Then, calculate how much stock, water and final concentration of each. Then, instead of doing a serial dilution, calculate making each of the above solutions using the weight/9% solution method. Pros and Cons of serial dilution method vs W/V % methodExplanation / Answer
D) #1 After considering 10mL of stock and weigh it (x gm) mix this with 100mL of water (1:10 ratio)
total volume of stock #1 will be = 110mL = 0.11L
mol of stock = x gm / mol wt of methylene blue in gm/mol
final concentration = mol of stock / 0.11L
#2 Consider 110mL of stock (from #1) and weigh it (y gm) , repeat the same procedure and find the concentrations
Same goes for #3 and #4
E) If all this is done in one single step then it is called w/v % solution method
F) Pros and cons of serial dilution method:
It gives you accurate concentrations of solute per mL through the series of progression and it is time consuming
process.
Pros and cons of W/V % method
Easy and takes less time to prepare a solution, concentration changes cannot be known
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