chem help?

Question

I need to make dilutions. The experiment is for pH and Im having a difficult time understanding. Stock solutions: 0.1 M sucrose; 0.2 M acetic acid; 0.2M sodium acetate; 0.2M anhydrous sodium carbonate; 0.2 M sodium bicarbonate.
A) calculate amount of 0.1M sucrose solution and amount dH2O needed to prepare 100mL of unbuffered 20mM sucrose.
B)Acetic Acid: calculate amount of each stock solution & amount of dH2O needed for 100mL of acetate buffer that contains 20mM sucrose, 40mM acetic acid, and 60mM sodium acetate.
C) calculate amount of each stock solution & amount dH2O needed to prepare 100mL of a bicarbonate buffer that contains 20mM sucrose, 22mM anhydrous sodium bicarbonate, and 28mM sodium bicarbonate.

Answer 1

it's a C1V1=C2V2
where C is concentration
V is volume
1 is initial condition
2 is final condition
for A) C1(initial concn) = 0.1 M
C2 (final concn) = 20mM = 0.02M
V2(final volume) = 100 mL thus using C1V1 = C2V2
V1 (initial/needed volume) = C2V2/C1
= 0.02M*100mL/0.1M
= 20 mL....

for B&C just use the formula you will get the volume needed for each reagent and if you add it, the sum will be less than the final volume of the solution containing the 3 reagents. the volume of water will then be the remaining volume of the solution needed to get 100 mL of the solution...

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