Question

26.9 g of solid lithium is combined with 20.0 grams of nitrogen gas. .

Answer 1

Answer:

The theoretical yield of

Li

3

N

is

20.9 g

.

Explanation:

Balanced Equation

6Li(s)

+

N

2

(

g

)

→

2Li

3

N(s)

In order to determine the theoretical yield, we must first find the limiting reactant (reagent), which will determine the greatest possible amount of product that can be produced.

Molar Masses

Li

:

6.941 g/mol

N

2

:

(

2

×

14.007

g/mol

)

=

28.014 g/mol

Li

3

N

:

(

3

×

6.941

g/mol Li

)

+

(

1

×

14.007

g/mol N

)

=

34.83 g/mol Li

3

N

Limiting Reactant

Divide the mass of each reactant by its molar mass, then multiply times the mole ratio from the balanced equation with the product on top and the reactant on bottom, then multiply times the molar mass of

Li

3

N

.

Lithium

12.5

g Li

×

1

mol Li

6.941

g Li

×

2

mol Li

3

N

6

mol Li

×

34.83

g Li

3

N

1

mol Li

3

N

=

20.9 g Li

3

N

Nitrogen Gas

34.1

g N

2

×

1

mol N

2

28.014

g N

2

×

2

mol Li

3

N

1

mol N

2

×

34.83

g Li

3

N

1

mol Li

3

N

=

84.8 g Li

3

N

Lithium produces less lithium nitride than nitrogen gas. Therefore, the limiting reactant is lithium, and the theoretical yield of lithium nitride is

20.9 g

.

Explanation: