Hydrated zinc sulfate gives off water when it is heated. $$\[ \mathrm{ZnSO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}(\mathrm{~s}) \rightarrow \mathrm{ZnSO}_{4}(\mathrm{~s})+\mathrm{xH}_{2} \mathrm{O}(\mathrm{~g}) \]$$ A student does an experiment to determine the value of $$\(\mathbf{x}\)$$ in $$\(\mathrm{ZnSO}_{4} \cdot \mathbf{x H}_{2} \mathrm{O}\)$$. step 1 The student weighs a sample of hydrated zinc sulfate. step 2 The student heats the sample of hydrated zinc sulfate. step 3 The student weighs the solid after heating. step 4 The student repeats step 2 and step 3 until the mass of solid after heating is constant. (i) State why the student does step 4. ................................................................................................................................... (ii) In an experiment, 0.574 g of $$\(\mathrm{ZnSO}_{4} \cdot \mathrm{xH}_{2} \mathrm{O}\)$$ is heated until the mass is constant. The mass of $$\(\mathrm{ZnSO}_{4}\)$$ that remains is 0.322 g . $$\(\left[M_{r}: \mathrm{ZnSO}_{4}, 161 ; \mathrm{H}_{2} \mathrm{O}, 18\right]\)$$ Determine the value of $$\(\mathbf{x}\)$$ using the following steps. - Calculate the number of moles of $$\(\mathrm{ZnSO}_{4}\)$$ remaining. .......................... mol - Calculate the mass of $$\(\mathrm{H}_{2} \mathrm{O}\)$$ given off. .......................... g - Calculate the number of moles of $$\(\mathrm{H}_{2} \mathrm{O}\)$$ given off. .......................... mol - Determine the value of $$\(\mathbf{x}\)$$. = ..........................

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