The discussion focuses on calculating the number of moles and mass of a sample of Copper Sulphate Pentahydrate (CuSO4•5H2O) containing 2.5x1020 formula units. The number of moles is calculated using the equation n=N/Na, resulting in 0.000415 moles, where Na is Avogadro's number (6.02x1023). The mass is then determined using m=nM, yielding a mass of 0.10369 grams, with M being the molar mass of CuSO4•5H2O (249.69 g/mol). The term 'formula units' is discussed as synonymous with 'molecules' for practical purposes.
PREREQUISITESChemistry students, educators, and anyone involved in laboratory work or chemical calculations, particularly those focusing on stoichiometry and solution preparation.
There was another part to this question and it asked how many moles of this substance are in this sample? Would that not just be the same as the answer to a)?epenguin said:Yes but that looks correct. I have got through a lifetime without ever hearing the term 'formula units'. Unnecessary IMO and I expect you will forget it, like those formulae you used. All it means is 'number of molecules' right? Which would see you through. I expect this pedantry is because CuSO4.5H2O isn't strictly a molecule but, oof, it's just like one for this purpose.