A compound has an empirical formula of AB and a molar mass of 90 g/mol. What is its
molecular formula? (Molar mass of AB = 30 g/mol)

A3B3

Explanation:

Molecular formula = n x empirical formula

(AB) n = 90

MM of AB = 30 g/mol

30n = 90

Divide both side by the coefficient n i.e 30

n = 90/30 = 3

Molecular formula = n x empirical formula

Molecular formula = n x (AB)

Molecular formula = 3(AB) = A3B3

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-