CHEMISTRY QUESTION

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>>8577408

>>8577412
I believe it means [math]x[/math] of the compound given, for example 2H20 or 3H20 or 4H20

>>8577408
its a molar ratio of how many water molecules per molecule of sodium sulfate, its supposed to be a "multiply by" dot

>>8577408
Here's the solution:
1. Get the proper masses by subtracting the mass of the crucible:
anhydrous Na2SO4: 1.42g, 142.04 g/mol
hydrated: 3.22g, x g/mol

2. There is a linear relationship between moles and mass, so use this to find the molar mass of the anhydrous compound given its mass is 3.22g:
1.42(g)/142.04(g/mol) = 3.22(g)/a
a = 322.09g/mol (the molar mass of the compound is being scaled linearly by x amount of water molecules, which each have a molar mass of 18 g/mol)

3. We know that _per mole_ of hydrated compound, Na2SO4 makes up 142.02g of the total 322.09g. So subtract the mass of the hydrated compound from that of the anhydrous to get the contribution of water. (The mass of water in one mole of the hydrated compound)

322.09g (water+Na2SO4) - 142.04g (Na2SO4) = 180.05g (water)

4. Calculate the moles of water present in one mole of the hydrated compound.

180.05(g)/18(g/mol) = 10mol H2O

5. The overall formula is Na2SO4*10H2O

>>8577469
Awesome! Thanks a lot man!