Question:
The crystalline salt Na2So4. XH2O on heating loses 55.9% of its weight. The formula of the crystalline salt is? Explain in detail.

Answer:
The given crystalline salt is Na2So4. XH2O. On heating, it loses 55.9% of its weight. Let's determine the formula of the crystalline salt by following the given steps:


- The crystalline salt is Na2So4. XH2O.
- On heating, it loses 55.9% of its weight.


- To determine the formula of a compound, we need to calculate the number of moles of each element present in the compound.
- The ratio of the moles of different elements will give us the formula of the compound.


- The molar mass of Na2So4 is calculated as follows:
- Molar mass of Na = 23 g/mol (atomic mass of Na)
- Molar mass of S = 32 g/mol (atomic mass of S)
- Molar mass of O = 16 g/mol (atomic mass of O)
- Molar mass of Na2So4 = 2(23) + 32 + 4(16) = 142 g/mol
- Let's assume the weight of Na2So4. XH2O is W grams.
- As per the given information, Na2So4. XH2O loses 55.9% of its weight on heating. This means the remaining weight after heating is 100% - 55.9% = 44.1% of the original weight.
- The weight of Na2So4 after heating is 44.1/100 * W grams.
- The number of moles of Na2So4 can be calculated using the formula:
- Moles = Weight / Molar mass
- Moles of Na2So4 = (44.1/100 * W) / 142


- The molar mass of H2O is calculated as follows:
- Molar mass of H2O = 2(1) + 16 = 18 g/mol
- The weight of H2O in Na2So4. XH2O is calculated as follows:
- Weight of H2O = W - (44.1/100 * W)
- The number of moles of H2O can be calculated using the formula:
- Moles = Weight / Molar mass
- Moles of H2O = (Weight of H2O) / 18


- The ratio of moles of Na2So4 to moles of H2O gives us the value of X.
- X = Moles of H2O / Moles of Na2So4


- The formula of the crystalline salt is Na2So4. XH2O, where X represents