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4. A 120.0 mg sample of a lead acetate hydrate, Pb(C2H3O2)2 × xH2O was heated to drive off the waters of hydration. The cooled residue had a mass of 103.0 mg. Calculate the value of x in the chemical formula. Show your work with Equation Editor.

Respuesta :

Answer: The value of x in the chemical formula is 3.

Explanation:

Molecular mass of [tex]Pb(C_2H_3O_2)_2.xH_2O=325+18x g[/tex]

Molecular mass of  [tex]Pb(C_2H_3O_2)_2[/tex] = 325 g

[tex]Pb(C_2H_3O_2)_2.xH_2O\rightarrow Pb(C_2H_3O_2)_2+xH_2O[/tex]

Thus (325+18x) g of [tex]Pb(C_2H_3O_2)_2.xH_2O[/tex] on heating gives = 325 g of [tex]Pb(C_2H_3O_2)_2[/tex]

0.120 g of [tex]Pb(C_2H_3O_2)_2.xH_2O[/tex] on heating should give =[tex]\frac{325}{325+18x}\times 0.120g[/tex] of [tex]Pb(C_2H_3O_2)_2[/tex] which is given to be equal to 0.103 g

Thus [tex]\frac{325}{325+18x}\times 0.120=0.103[/tex]

Solving for x

[tex]x=3[/tex]

Thus the value of x in the chemical formula is 3.

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