We just may apply expression for molarity.
According to molarity (or molar concentration) expression:
We know that
Now, let us calculate the mass of
- For carbon, C, we know that there are 16 atoms for every molecule of methylene blue. Its atomic mass is 12.01 amu (atomic mass units), so there are
#12.01 cdot 16 = color(blue) 192.16#amu of C per molecule. Analogously, we can say that there are 192.16 g of C per mol of methylene blue (atomic mass on amu and molar mass on g/mol are equivalent).
We just may apply this method to all the elements on methylene blue molecule:
- For hydrogen:
#1.01 cdot 18 = color(blue) 18.18#g/mol.
- For nitrogen:
#14.01 cdot 3 = color(blue) 42.03#g/mol.
- For sulphur:
#32.07 cdot 1 = color(blue) 32.07#g/mol.
- For chlorine:
#35.43 cdot 1 = color(blue) 35.43#g/mol.
The sum of all being:
If we need 0.04 mol of