Hi
The question is already solved, its from a book. I don't get the bold step or rather why it is 1000?
Calculate the volume of hydrogen gas evolved at 273K and 1atm pressure when 0.623g of Mg reacts with 27.3 cm3 of 1.25mol dm-3 HCl.
Mg(s) + 2HCl(aq) -> H2(g) + MgCl2(aq)
Mg: 0.623/24.31 = 2.56 x 10-2 mol
HCl: 1.25 x (27.3/1000) = 3.41 x 10-2 mol
Thanks!