Respuesta :
Answer : The chemical symbol for this element is, (La)
Explanation : Given,
Mass of [tex]XCl_3[/tex] = 0.760 g
Mass of [tex]XI_3[/tex] = 1.610 g
The given chemical reaction is:
[tex]2XCl_3+3I_2\rightarrow 2XI_3+3Cl_2[/tex]
First we have to calculate the moles of [tex]XCl_3[/tex] and [tex]XI_3[/tex].
[tex]\text{Moles of }XCl_3=\frac{\text{Mass of }XCl_3}{\text{Molar mass of }XCl_3}[/tex]
Molar mass of Cl = 35.5 g/mole
Let the molar mass of element 'X' be, M
[tex]\text{Moles of }XCl_3=\frac{0.760}{[M+3(35.5)]}[/tex]
and,
[tex]\text{Moles of }XI_3=\frac{\text{Mass of }XI_3}{\text{Molar mass of }XI_3}[/tex]
Molar mass of I = 126.9 g/mole
Let the molar mass of element 'X' be, M
[tex]\text{Moles of }XI_3=\frac{1.610}{[M+3(126.9)]}[/tex]
From the balanced chemical reaction we conclude that,
The moles of ratio of [tex]XCl_3[/tex] and [tex]XI_3[/tex] is, 1 : 1
That means,
[tex]\frac{0.760}{[M+3(35.5)]}=\frac{1.610}{[M+3(126.9)]}[/tex]
[tex]\frac{0.760}{[M+106.5]}=\frac{1.610}{[M+380.7]}[/tex]
[tex]M=138.667g/mol[/tex]
From this we conclude that the element (X) is lanthanum (La) that has molecular weight, 138.667 g/mol.
Hence, the chemical symbol for this element is, (La)
