Ammonia, formed of 3 hydrogen atoms and a nitrogen atom, has an atomic weight of 17g/mol. (Actually 17.031g/mol if we're being picky.) This means that 17g of ammonia is one mole of ammonia. read more
This means that 17g of ammonia is one mole of ammonia. The number of molecules in a single mole of any compound is given by Avoadro’s constant, which is 6.023x10^23. There would be 6.023x10^23 molecules of ammonia in 17 grams of the substance. read more