You are given 7.80g of Bromine gas in a container. Under identical conditions, you have 12.8g of an unknown gas. What is the molar mass of the unknown gas?

- so, considering the molar mass of Bromine that I used was 159.808g/Mol, I did:
7.80g Br / 159.808g/mol = 12.8g unknown gas / molar mass of unknown gas

Molar mass of unknown gas = 262g/Mol

Is this correct?

I never saw a problem like this before but your solution looks ok to me.

To find the molar mass of the unknown gas, you can use the concept of stoichiometry.

1. Start by calculating the number of moles of bromine gas (Br2) using the given mass and the molar mass of bromine:
Moles of Br2 = mass of Br2 / molar mass of Br2
= 7.80 g / 159.808 g/mol

2. Now, use the balanced equation between bromine gas (Br2) and the unknown gas to establish a ratio:
Moles of Br2 / Molar mass of Br2 = Moles of unknown gas / Molar mass of unknown gas

3. Rearrange the equation to solve for the molar mass of the unknown gas:
Molar mass of unknown gas = (Moles of unknown gas) / (Moles of Br2) * (Molar mass of Br2)

Plugging in the known values, we have:
Molar mass of unknown gas = (12.8 g / 159.808 g/mol) * (molar mass of Br2)

Substitute the given molar mass of bromine (159.808 g/mol) and calculate:
Molar mass of unknown gas = (12.8 g / 159.808 g/mol) * 159.808 g/mol

Calculating further,
Molar mass of unknown gas ≈ 12.8 g.

Therefore, it appears that the molar mass of the unknown gas is approximately 12.8 g/mol.