Chemistry Question

[TGW_400ex]

How do you calculate the molar mass of a single molecule that weighs 6.90 x 10^-23 grams?

first you need to determine what you have a molecule of
eg water or H2O

then you get the atomic weight of each element in that molecule
eg:
H 1.00794
O 15.9994

next you multiply the atomic weight of each element by the number of atoms in the formula
eg:
H: 2x1.00794=2.01588
O 1X15.9994+15.9994

Finally add the results
2.01588+15.9994=20.0317 is the molar mass of water