[vijay_cluster]

0.1 g of a metal, of specific heat 0.214, on dissolution in HCl displaced 124.4 ml of dry hydrogen at STP. The atomic weight of the metal is ____ 
 Answer is given At.wt of metal is 27 .how is it possible any one help me Please
I tried the problem from the formula At.wt x sp.heat = 6.4 for metals but it is getting 29.9

[Borek]

Dulong-Petit law is only approximate, so it gives you only order of magnitude. Stoichiometry gives much more precise information. Not knowing metal valence you can determine only equivalent weight, not atomic weight - but combining both informations you can get the exact answer.