Answer to Question #86792 in General Chemistry for Enci Peng

Question

Experimental yield is 29 volume of hydrogen gas collected

Temperature of water/gas = 22 Celsius

Atmospheric pressure 765.8 mm Hg

1Mg+2HCI —> 1MgCl2+1H2

1. Using the balance chemical equation, solve for the volume of H2 that theoretically should be produced

2. Determine the percent yield by using the experimental yield/theoretical yield x 100

Answer 1

m(Mg) = 36 g.

n(Mg) = m(Mg) / M(Mg) = 36 g / 24 g/mol = 1.5 mol.

1.5mol                           x mol

   Mg+2HCI —> MgCl₂+H₂↑

 1mol                             1mol

n(H₂) = x = 1.5 mol.

p(H₂)×V(H₂)=n(H₂)×R×T(H₂)

R = 62.4 L×mm Hg / mol×K

T_K = t_C + 273.15 = (22+273.15) K = 295.15 K.

1)     V(H₂)_theor = n(H₂)×R×T(H₂)/ p(H₂) = 1.5 mol × 62.4 L×mm Hg / mol×K × 295.15 K / 765.8 mm Hg = 36.07 L.

2)     η = V(H₂)_exper / V(H₂)_theor = 29 L / 36.07 L × 100% = 80.3992% ≈ 80.4%.