Question

How many molecules of glucose in a xenopus oocyte if the total volume is 10 ul and the concentration of glucose is 10 mm?

Answer 1

There are 6.0×1015lmolecules of glucose in the oocyte.

Explanation:

The formula for molarity is:

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯∣∣∣aaMolarity=moleslitresaa∣∣∣−−−−−−−−−−−−−−−−−−−−−

or

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯∣∣∣aaM=nVaa∣∣∣−−−−−−−−−−−−

In your problem,

M=10 mmol/L=1.0×10-3lmol⋅L-1
V=10 µL=1.0×10-5lL

∴ n=MV=1.0×10-3lmol1L×1.0×10-5L=1.0×10-8lmol

Now, we can use Avogadro's number to calculate the number of molecules.

Molecules=1.0×10-8mol×6.022×1023lmolecules1mol=6.0×1015lmolecules