What is the empirical formula of a substance that consists of 32.86% potassium and 67.14% bromine? A)KBr B)K₂Br C)KBr₂ D)K₂Br₃

Question

Quizplus · Accepted Answer

To find the empirical formula, we need to determine the lowest whole number ratio of the atoms present in the compound.

Assume we have 100g of the compound. 
Thus, we have 32.86g potassium and 67.14g bromine.

Next, we convert these masses into moles: 
moles of K = 32.86g / 39.10 g/mol (molar mass of K) ≈ 0.8400 mol 
moles of Br = 67.14g / 79.90 g/mol (molar mass of Br) ≈ 0.8411 mol

Next, we divide each of the moles by the smaller value to get a ratio of whole numbers: 
0.8400 mol K / 0.8400 mol = 1.000 
0.8411 mol Br / 0.8400 mol = 1.001

The ratio of the elements is therefore approximately 1:1, so the empirical formula is KBr.

What Is the Empirical Formula of a Substance That Consists