What mass in grams (theoretical yield) of hydrogen is produced by the reaction of 31.3 g of
magnesium with 2.12 g of water?
Mg(s) + 2H20 (1) ► Mg(OH)2 (s) + H2 (g)
O 0.474
O 0.0593
2.71
O 0.119
O 0.237

Respuesta :

The percent yield is 74.4 %.

Fe₃O₄ + 4H₂ → 3Fe + 4H₂O

First, calculate the theoretical yield of H₂O.

Theor. yield =

0.112 g H

2

×

1 mol H

2

2.016 g H

2

×

4 mol H

2

O

4 mol H

2

×

18.02 g H

2

O

1 mol H

2

O

=

1.001 g H

2

O

Now calculate the percent yield.

% yield =

actual yield

theoretical yield

×

100

%

=

0.745 g

1.001 g

×

100

%

=

74.4

%

The mass in grams (theoretical yield) of hydrogen is produced is considered to be 0.119 g H2.

Calculation of the mass:

Since

Mass of Mg = 31.3 g

Mass of H2O = 2.12 g

First, we have to determine the mole

So,

Mole of Mg = mass of Mg / molar mass of Mg

= (31.3 g ) / (24.30 g/mol )

= 1.28 mole

And,

Mole of H2O = (2.12g ) / (18.01g /mol )

= 0.117 mole

As per the chemical reaction:

2 mole of H2O react with 1 mole of Mg

So, 0.117 mole of H2O will react with mole of Mg is

Now

= ( 1 mol Mg / 2 mol H2O ) * 0.117 mol H2O

= 0.058 mole of Mg

Now

1 mole of Mg produce , 1 mole of H2

So,

0.058 mole of Mg will produce 0.058 mole of H2

Now, determine the mass of H2

= Molar mass of H2 * mole of H2

= 2 * 0.058

= 0.116 g

= 0.119

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