Question

An element X has a dibrom ide with the empirical formula XBr2 and a dichloride with the empirical formula XCI2. The dibromide is completely converted to the dichloride when it is heated in a stream of chlorine according to the reaction $$XBr2 + Cl2 → XCI2 + Br2$$ When 1.500 g XBr2 is treated, 0.890 g XCI2 results. (a) Calculate the atomic mass of the element X. (b) By reference to a list of the atomic masses of the elements, identify the element X.

Answer 1

58.85 g/mol is the atomic mass of the element X.

The element X is cobalt.

Step-by-step explanation:

`XBr_2 + Cl_2\rightarrow XCI_2 + Br_2`

Moles of
`XBr_2=(1.500 g)/(M)` mol

According to reaction, 1 mole of
`XBr_2` gives 1 mole of
`XCl_2`. then
`(1.500 g)/(M)` mol of [tex[CBr_2[/tex] will give:

`(1)/(1)* (1.500 g)/(M)` mol=\frac{1.500 g}{M}[/tex] mol[/tex] of
`XCl_2`

Mass of
`(1.500 g)/(M)` moles of
`XCl_2` =0.890 g (given)

Atomic mass of element X =m

M=
`m+79.9 g/mol* 2`

M'=
`m+35.45g/mol* 2`

`(1.500 g)/(M)* M'=0.890 g`

`(1.500 g)/(m+79.9 g/mol* 2)* (m+35.45g/mol* 2)=0.890 g`

m = 58.806 g/mol

58.56 g/mol is the atomic mass of the element X.

m = 58.806 g/mol ≈ 58.93 g/mol atomic mass of cobalt

The element X is cobalt.