Final answer:
To calculate the empirical formula, determine the molar amounts of each element in the compound. For water, the empirical formula is H2O with a ratio of 2 hydrogen atoms to 1 oxygen atom. To find the number of moles of water in copper sulphate crystals, compare the mass of water lost during heating to the mass of the copper sulphate.
The molecular formula can be calculated by comparing the molar mass of the empirical formula to the molar mass of the compound.
Step-by-step explanation:
To determine the empirical formula of a compound, you need to know the molar amounts of each element in the compound. This can be calculated by using the masses of the elements and converting them to moles. Once you have the molar amounts, you can write the empirical formula based on the ratios of the elements. For example, the empirical formula for water (H2O) indicates a ratio of 2 hydrogen atoms to 1 oxygen atom.
To determine the number of moles of water in copper sulphate crystals, you need to compare the mass of the water lost during heating to the mass of the copper sulphate. Using the given values, you can calculate the number of moles of water present in the crystals.
If the molar mass of the compound is known, you can use the information about the empirical formula and the molar mass to calculate the molecular formula. The molecular formula gives the actual number of atoms of each element in a compound. By comparing the molar mass of the empirical formula to the molar mass of the compound, you can determine the multiple of the empirical formula needed to obtain the molecular formula.