A sample of a compound of mercury and bromide with a mass of .389 was found to contain .111g bromine. Its molar mass was found to be 561 g mol-1. What are its empirical and molecular formula. Please detail each step in the process. Thanks in advance!

Omitting coefficients:

..........Hg + Br ==> HgBr
..........x..0.111....0.389
So Hg must be 0.389-0.111 = 0.278g

moles Hg = 0.278/200.6 =0.00139
moles Br = 0.111/79.9 = 0.00139

So ratio is 1:1 and formula is HgBr.
Check my work.

Can you explain, why did you omit coefficients? and what about the molecular formula, i think you only did the empirical.

DrBob222 is SOO close... Yes, the ratio is 1:1, but how does the molecular mass of HgBr compare to the molecular mass given in the problem (this will give you the answer)?

Molecular formula is Hg2Br2. you divide the molecular mass by the molar mass of the imperical formula

To find the empirical formula and molecular formula of the compound, we need to follow these steps:

Step 1: Convert the masses of each element to moles.

Given:
Mass of the compound = 0.389 g
Mass of bromine = 0.111 g

Molar mass of bromine (Br) = 79.904 g/mol

Number of moles of bromine = mass of bromine / molar mass of bromine
= 0.111 g / 79.904 g/mol
= 0.001390 mol

Step 2: Determine the mole ratio of the elements.

Since the compound contains only mercury (Hg) and bromine (Br), the mole ratio is 1:1.

Step 3: Write the empirical formula using the mole ratio.

The empirical formula is the simplest whole number ratio of atoms in a compound. In this case, since we have a 1:1 mole ratio, the empirical formula is HgBr.

Step 4: Calculate the empirical formula mass.

Empirical formula mass = molar mass of HgBr

Molar mass of HgBr = [molar mass of Hg (200.59 g/mol) + molar mass of Br (79.904 g/mol)] = 280.494 g/mol

Step 5: Calculate the number of empirical formula units present in the compound.

Number of empirical formula units = mass of the compound / empirical formula mass
= 0.389 g / 280.494 g/mol
= 0.001386 mol

Step 6: Calculate the molecular formula.

The molecular formula represents the actual number of atoms of each element in a compound. To find the molecular formula, we need to determine the ratio between the empirical formula units and the actual formula units.

Number of empirical formula units = number of actual formula units * multiplier

To calculate the multiplier, divide the molar mass of the compound by the empirical formula mass:
multiplier = molar mass / empirical formula mass
= 561 g/mol / 280.494 g/mol
= 2

Number of actual formula units = number of empirical formula units * multiplier
= 0.001386 mol * 2
= 0.002772 mol

Since the empirical formula is HgBr, the molecular formula is the same: HgBr.

Therefore, the empirical formula and molecular formula of the compound are HgBr.