Final answer:
To determine the empirical formula of a compound containing cobalt and oxygen, the mass of each element is converted to moles and then divided by the smallest number of moles to get the simplest whole number ratio. The resulting empirical formula for this compound is Co2O3.The correct answer is option b.
Step-by-step explanation:
To find the empirical formula of the compound containing cobalt and oxygen, we start by determining the mass of oxygen in the compound. Since the original mass of the compound is 7.500 grams and the mass of cobalt after heating is 5.331 grams, we subtract the mass of cobalt from the original mass to find the mass of oxygen:
Mass of oxygen = Original mass - Mass of cobalt
= 7.500 g - 5.331 g
= 2.169 g
Next, we convert the masses to moles by dividing by the molar mass of each element:
Moles of Co = 5.331 g / (58.93 g/mol) = 0.09043 mol
Moles of O = 2.169 g / (16.00 g/mol) = 0.13556 mol
We then divide both moles by the smallest number of moles to find the simplest whole number ratio:
Moles of Co: 0.09043 mol / 0.09043 mol = 1
Moles of O: 0.13556 mol / 0.09043 mol = 1.50, which we can round to 3/2
To get a whole number ratio, multiply both by 2:
Moles of Co x 2 = 2
Moles of O x 2 = 3
Thus, the empirical formula of the compound is Co2O3, which corresponds to option b) Co2O3.