It is often possible to change a hydrate into an anhydrous compound by heating it to drive off the water (dehydration). A 45.91 gram sample of a hydrate of MnSO4 was heated thoroughly in a porcelain crucible, until its weight remained constant. After heating, 37.07 grams of the anhydrous compound remained. What is the formula of the hydrate

Respuesta :

Answer: The formula of the hydrate is [tex]MnSO_4.2H_2O[/tex]

Explanation:

Decomposition of hydrated manganese sulphate is given by:

[tex]MnSO_4.xH_2O\rightarrow MnSO_4+xH_2O[/tex]

Molar mass of [tex]MnSO_4[/tex] = 151.0 g/mol

According to stoichiometry:

(151.0+18x) g of [tex]MnSO_4.xH_2O[/tex] decomposes to give 151.0 g of [tex]MnSO_4[/tex]

Thus 45.91 g of [tex]MnSO_4.xH_2O[/tex] decomposes to give= [tex]\frac{ 151.0}{151.0+18x}\times 45.91g[/tex]  of [tex]MnSO_4[/tex]

Also we are given : 37.07 g of  [tex]MnSO_4[/tex] is produced

Thus we can equate the two equations:

[tex]\frac{ 151.0}{151.0+18x}\times 45.91=37.07[/tex]

[tex]x=2[/tex]  

Thus the formula of the hydrate is [tex]MnSO_4.2H_2O[/tex]