An unknown compound containing tellurium and bromine is analyzed and it is determined that 28.53% of the compound by mass is
composed of tellurium.
How many moles of Te are present in 100.00 g of the compound?

The correct answer is 0.22 mol Te.

Explanation:

First, we have to calculate the mass of Te in the sample. We simply multiply the sample mass by the percentage of Te (28.53%= 28.53/100)

100.00 g x 28.53/100 = 28.53 g Te

The molar mass of Te is 127.60 g. Thus, the mass of 1 mol of Te is 127.60 g. With this, we calculate how many moles of Te there are in 28.53 g of Te:

28.53 g Te x 1 mol Te/127.60 g Te= 0.223 mol ≅ 0.22 mol