Suppose you dissolve 52.2 g of na2co3·xh2o in enough water to make 5.00 l of solution. the final concentration of the solution was found to be 0.0366 m. determine the integer x in the hydrate: na2co3·xh2o. round your answer to the nearest integer.

x = 10.

Explanation:

M = (no. of moles of Na₂CO₃·xH₂O) / (Volume of the solution (L)).

∴ no. of moles of Na₂CO₃·xH₂O = (M of Na₂CO₃·xH₂O)*(Volume of the solution (L)) = (0.0366 M)*(5.0 L) = 0.183 mol.

∵ no. of moles = mass/molar mass

∴ Molar mass of Na₂CO₃·xH₂O = (mass of Na₂CO₃·xH₂O)/(no. of moles of Na₂CO₃·xH₂O) = (52.2 g)/(0.183 mol) = 285.245 g/mol.

∵ The molar mass of Na₂CO₃·xH₂O = Molar mass of Na₂CO₃ + x (molar mass of water).

The molar mass of Na₂CO₃·xH₂O = 285.245 g/mol.

Molar mass of Na₂CO₃ = 105.9888 g/mol.

molar mass of water = 18.0 g/mol.

∴ 285.245 g/mol = 105.9888 g/mol + x (18.0 g/mol).

x (18.0 g/mol) = 285.245 g/mol - 105.9888 g/mol = 179.257 g/mol.

∴ x = (179.257 g/mol)/(18.0 g/mol) = 9.958 ≅ 10.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

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