Final answer:
To determine the number of moles of lactic acid with a given number of oxygen atoms, divide the number of oxygen atoms by Avogadro's number to get the moles of oxygen, and then divide again by 3, as each lactic acid molecule contains 3 oxygen atoms.
Step-by-step explanation:
To calculate how many moles of lactic acid contain 4.5 × 10²⁴ atoms of oxygen, we need to first recall that lactic acid has the chemical formula C3H6O3, which means each molecule has 3 oxygen atoms. Avogadro's number, 6.022 × 10²³, is the number of atoms in one mole. To find the number of moles of oxygen atoms we have:
Number of moles of O atoms = 4.5 × 10²⁴ atoms / 6.022 × 10²³ atoms/mole
Then, we convert moles of oxygen atoms to moles of lactic acid:
Number of moles of lactic acid = (Number of moles of O atoms) / 3
Without calculation, we see that as there are 3 oxygen atoms in each molecule of lactic acid, the number of moles of lactic acid will be a third of the number of moles of oxygen atoms.