Final answer:
To calculate the number of moles of Na2SO4 in 284.078 g of Na2SO4, we use the formula moles = mass / molar mass. The molar mass of Na2SO4 is 142.042 g/mol, so the number of moles is 2.000.
Step-by-step explanation:
The question asks for the number of moles of Na2SO4 present in 284.078 g of Na2SO4. To calculate this, we first need to find the molar mass of Na2SO4, which is the sum of the atomic masses of the elements in the compound. The molar mass of Na2SO4 is 46.98 g/mol for Na, 32.06 g/mol for S, and 15.999 g/mol for O, so the molar mass of Na2SO4 is (2 * 46.98) + 32.06 + (4 * 15.999) = 142.042 g/mol.
Next, we can use the formula: moles = mass / molar mass. Plugging in the values, we get: moles = 284.078 g / 142.042 g/mol = 2.000 mol.
Therefore, there are 2.000 moles of Na2SO4 present in 284.078 g of Na2SO4.