1) You have a protein at 20 ug/ml. Its MW =10,000. What is the concentration in molarity? Show work please!

2) You are asked to make 30 mL of a solution at 0.03M using the 0.10M stock solution. How many mililliliters of water do you use to make this solution? How many millilters of the 0.10 M stock solution do you use to make this solution? (0.358 gr of naphthol yellow used). Show work please!

Thank you!

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1. 1. Convert 20 ug/mL to g/L. Take 1000 mL (= 1L)
20 ug/mL x 1000 mL = 20,000 ug in that L.
How many grams is that.
20,000 ug x (1 g/1E6 ug) = ? grams.
mols = grams/molar mass and M = mol/L.

2.
mL1 x M1 = mL2 x M2
30 x 0.03 = mL2 x 0.1M
Solve for mL2. That's the mL of the stock you will take. Pipet out that amount of the stock and make up to 30.0 mL. Assuming the volumes are additive that will be 30-9 = 21 BUT a good chemist NEVER assumes the volumes are additive. What you ALWAYS do is take the stock and ADD whatever amount of water is necessary to make 30.0 mL.

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