Final answer:
By calculating the moles of lead and oxygen left after heating Pb3O4, we find that the ratio of Pb to O is approximately 3:1. The empirical formula for the second oxide of lead formed, therefore, is PbO.
Step-by-step explanation:
To find the empirical formula for the second oxide of lead that forms when 2.750 g of Pb3O4 is heated and produces 0.0640 g of oxygen gas, we can use the mass of lead and oxygen in the product. Since the total mass of the compound doesn't change, the mass of lead in the second oxide can be calculated by subtracting the mass of the released oxygen from the initial mass of Pb3O4. This gives us 2.750 g - 0.0640 g = 2.686 g of lead. Using the relative atomic masses (Pb = 207, 2 u and O = 16,0 u), we can convert this mass into moles to find the ratio of lead to oxygen in the second oxide.
Finding the moles of lead: 2.686 g Pb / 207.2 u = 0.01297 moles Pb.
Finding the moles of oxygen: 0.0640 g O / 16.0 u = 0.00400 moles O.
The mole ratio of Pb to O is 0.01297 moles Pb : 0.00400 moles O, which simplifies approximately to a 3:1 ratio. Therefore, the empirical formula of the second oxide is PbO.
Note: The detailed calculations were not shown here but would involve confirming that the ratio is close enough to 3:1 after dividing both amounts by the smallest number of moles.