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!

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.

1) To find the concentration in molarity, we need to know the formula:

Molarity (M) = (Concentration in grams per liter)/(Molecular weight in grams per mole)

In this case, the concentration is given in micrograms per milliliter, so we need to convert it to grams per liter. To do this, we multiply by 1000 (since there are 1000 micrograms in a milligram and 1000 milliliters in a liter).

20 ug/ml * (1 mg/1000 ug) * (1 g/1000 mg) * (1000 ml/1 L) = 0.02 g/L

Now we can plug in the values into the formula:

M = 0.02 g/L / 10,000 g/mol

Simplifying, we get:

M = 2 x 10^-6 mol/L

So the concentration in molarity is 2 x 10^-6 M.

2) The formula for dilution is:

C1V1 = C2V2

Where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.
In this case, we are given C1 = 0.10 M and V1 (the volume of the stock solution) is unknown.
C2 = 0.03 M and V2 (the final volume) is 30 mL.

Now, we can calculate V1 by rearranging the formula:

V1 = (C2V2)/C1

V1 = (0.03 M * 30 mL) / 0.10 M

V1 = 9 mL

So, you will use 9 mL of the 0.10 M stock solution.

To find the volume of water required, we can subtract the volume of the stock solution used from the final volume:

Volume of water = V2 - V1
Volume of water = 30 mL - 9 mL
Volume of water = 21 mL

So, you will use 21 mL of water to make the solution.