Answer to Question #149564 in Physical Chemistry for Elly

Question

An alloy with density 2.85 g/cm³ consists of 93.7% Al and 6.3%Cu by mass. 0.691cm³ of alloy reacts with HCl(aq). If all Al and none Cu reacts with acid, find mass of H2 obtained.

Answer 1

Solution.

$m = \rho \times V$

m = 1.97 g

$m(Al) = 0.937 \times 1.97 = 1.85 g$

$n(H2) = \frac{n(Al) \times 3}{2}$

$n(Al) = \frac{1.85}{26.98} = 0.07 \ mol$

n(H2) = 0.105 mol

$m(H2) = 0.105 \times 2 = 0.21 g$

Answer:

m(H2) = 0.21 g