Help with calculations

hya sara,

Don't you use Avogadro's Number? (The number of molecules in a mole of a compound) = 6.02 x 10^23 / mol ...

(V1)(C1) = (V2)(C2)

(1.5 mL)*(3 x 10^9 cells per mL) = (0.05 mL)( C2 ) => 9 000 000 cells/L

Molarity is commonly in the unit mol/L

9 000 000 cells/L (divided by) 6.02 x 10^23 mol-1 = # (cells*mol) / L

For the second part, you add 5 microliter to a volume of 45 microliter, so essentially you have diluted your ribonuclease 10 times. So if your initial concentration of ribonuclease was 100 microgram per ml, now it will be 10 microgram per ml. That equals 0.01 microgram per microliter.


Thanks, that helps a lot. Do you have any idea for the 1st calculation?

Sara