Question

Active mass of 2 mole of NaCl kept in 4 litre at NTP

Answer 1

substance's molar mass. For atoms, molecules, etc. the molar mass is equal to the atomic weight (or sum of atomic weights, in the case of molecules) in grams. This can be proved by the following:

(X amu/type of item) x (1.66x10^-24 grams/ 1 amu) x (6.02x10^23 items/ 1 mole) =

X grams/mole


Basically, take the atomic weights of Sodium (~23 amu) and Chlorine (~35.5 amu) and add them up. Then, take the units (amu) and change it to grams, and you've got your answer. This amounts to the "short version" of the proof given above.

Weight NaCl: 23 amu + 35.5 amu = 58.5 amu

Molar mass NaCl: 58.5 grams/mole

2 moles NaCl =

2 moles x 58.5 grams/mol = 117 grams