Question

Analysis of a compound containing potassium, chromium, and oxygen determines that in a 3.34g sample, 0.89g is potassium, 1.18g is chromium, and 1.27g is oxygen. What is the empirical formula of the compound?

a) KCrO
b) K₂CrO₂
c) K₂Cr₂O₇
d) KCrO₃

Answer 1

The empirical formula of the compound is KCrO3.

Step-by-step explanation:

To find the empirical formula of the compound, we need to determine the mole ratios between the elements. First, we need to convert the given masses of potassium, chromium, and oxygen to moles using the molar mass of each element. The molar mass of potassium (K) is 39.10 g/mol, chromium (Cr) is 52.00 g/mol, and oxygen (O) is 16.00 g/mol. So, the number of moles of potassium is 0.89 g / 39.10 g/mol = 0.0228 mol, chromium is 1.18 g / 52.00 g/mol = 0.0227 mol, and oxygen is 1.27 g / 16.00 g/mol = 0.0794 mol.

Next, we divide each mole value by the smallest mole value to get the simplest mole ratio. In this case, the smallest mole value is 0.0227 mol. Dividing the mole values by 0.0227 mol gives us a ratio of approximately 1:1:3 for potassium, chromium, and oxygen, respectively. Therefore, the empirical formula of the compound is KCrO3, option (d).