Question

For the molecular compound, magnesium chloride dihydrate: Calculate the percentage composition of chlorine in the compound.

Answer 1

Explanation:

The correct formula for magnesium chloride is

MgCl

2

.

To determine the percent composition of

Mg

, divide the molar mass of

Mg

by the molar mass of

MgCl

2

and multiply by

100

%

.

M

Mg

:

24.305 g/mol

(atomic weight of periodic table in g/mol)

M

MgCl2

:

(

24.305

g/mol Mg

)

+

(

2

×

35.45

g/mol Cl

)

=

95.305 g/mol

Percent composition of Mg

% Mg

=

24.305

g/mol

95.205

g/mol

×

100

%

=

25.529% Mg

The percent composition of

Mg

in

MgCl

2

is

25.529%

.