0.048 g of magnesium was reacted with excess dilute Hydrochloric acid at room temperature & pressure. The hydrogen gas given off was...

The experiment could be done in a Wolff's bottle fitted
with an exit tube and a long neck funnel. The other end of the exit tube should be bent
and trapped under water. A gas jar of 0.05 Lit. capacity, filled with water has to be
inverted over that end. The hydrogen gas will be collected at the gas jar through
downward displacement of water. The volume of gas ollected can be calculated by
considering the stoichiometries

                Mg +
2HCl react to produce MgCl2 + H2 (g)

   24 g or one gm-atom
Mg produces            22.4 lit H2 (g) at NTP

 0.048 g
Mg produces       22.4*0.048/24 = 0.0448 lit H2 (g) at
NTP

Now at Room temp (higher than NTP), this gas will
expand and the final volume can be obtained from gas law eqn. V/T =
constant

so V1/T1 = V2/T2

or
 0.0448/273 = v/298

or v= 0.0448*298/273 = 0.0489 Lit. =
0.05 lit. (approx.)