3.2%
Объяснение:
dilute sulfuric acid reacts with zinc to produce hydrogen
zn + h2so4 = znso4 + h2
find the mass of gas released
n (h2) = n (zn) = m (zn) / mr (zn) = 13/65 = 0.2 mol
then the mass of hydrogen m (h2) = n * mr = 0.2 * 2 = 0.4 g
mass of solution at the end of the reaction
m (solution) = m (solution h2so4) + m (zn) - m (h2) = 1000 + 13-0.4 = 1012.6 gr
we put in a mass of zinc sulfate
n (znso4) = n (zn) = 0.2 mol
m (znso4) = n * mr = 0.2 * (65 + 32 + 64) = 32.2 gr
then the mass fraction of sulfate w = m (znso4) * 100% / m (solution) = 32.2 * 100 / 1012.6 = 3.2%
