A 2.06g sample of agno3•xh2o is dissolved in an aqueous solution of excess nacl. The resulting agcl precipitate is filtered off and is found to have a mass of 1.32 g. What is the value of x in agno3•xh2o?

3

Explanation:

NaCl + AgNO₃ - --> NaNO₃ + AgCl.

Firstly, we will need to calculate the number of moles of AgCl produced. That is equal to the mass produced divided by the molar mass of AgCl.

The molar mass of AgCl = 108 + 35.5 = 143.5g/mol

The number of moles is thus 1.32/143.5 = 0.0092 moles

Since silver nitrate and silver chloride contains one atom of silver, it is only possible that their mole ratios are equal. Hence we say that 0.0092 moles of silver nitrate hydrate was dissolved.

Now we go on to calculate the molar mass of the silver nitrate hydrate.

The molar mass is simply the mass divided by the number of moles.

That is 2.06/0.0092 = 223.9 = 224g/mol

We can now calculate the value of x from here.

AgNO3. xH2O

(108 + 14 + 48) + x (2 + 16) = 224

170 + 18x = 224

18x = 224 - 170 = 54

18x = 54

x = 54/18 = 3