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Question

1) How many grams per liter would make a 1 micromolar glucose solution?

2) suppose you have stock solution concentration of 200 mM. If you wanted to dilute this solution to make a total of 20 ml of a 50mM solution, what volume of stock and water would you use in milililters.

3) how many grams of sucrose (MW 342.3) do you need to add to 3 liters of water in order to make a 250 milimolar solution

4) how many milligrams of sucrose do you need to add 300 mL of water in order to make a 45 micromolar sucrose solution

5) how How many milligrams per milliliter would make a 1 Miller molar sucrose solution

Answer 1

#1) Moles per liter = concentration... 1 mol of glucose = 180g

So 1 μMol of glucose would just be 180*10^-6 ....

#2) c1v1=c2v2 ... c1 = stock solution concentration(200mM), v1 = the volume we need to find(x), c2 = final solution concentration (50mM), v2 = final volume (20mL)

Now Lets just plug in those values (c1*v1=c2*v2) and solve the algebra... 200mM * x = 50mM * 20 mL

solving... x or v1 = 5mL stock volume

Now we take our final volume of 20 mL and subtract the stock volume...

20mL - 5 mL = 15 mL of water needed...

#3). (Molarity) = ((required weight in grams) * 1000 mL ) / (Mol weight) (volume mL)

250mM = 1000x / (342.2)(3000)

Rewriting as

0.250 = 1000x / (342.2)(3000)

solving...

x = 256.725 g

#4) same equation as above but different units...

(45*10^-6) = 1000x / (342.5) (300)

solving...

x = 0.00462375 g

#5) is similar to the first problem, but different units...

Remember that... Molarity = (moles of solute) / (liters of solution)

since 342.3 g = 1 mol of sucrose

then 342.3 g per 1000 mL would equal 1M

But we need 1mM or 0.001M

just multiply 342.3g by 0.001

so you would need 0.3423 mg/mL to make 1 mM of sucrose solution