Two hypothetical ionic compounds are discovered with the chemical formulas XCl2 and YCl2, where X and Y represent symbols of the imaginary elements. Chemical analysis of the two compounds reveals that 0.25 mol XCl2 has a mass of 100.0 g and 0.50 mol YCl2has a mass of 125.0 g.
a. What are the molar masses of XCl2 and YCl2?
We can figure this out by remembering that the formula for the molar mass of a chemical compound is the mass of the substance divided by the amount of the substance. Molar mass is given in the units g/mol (grams per mole). Since we are given both quantities in the problem above, we simply divide to get the number.
For XCl2, we are told that 0.25 moles has a mass of 100 g. So the molar mass is 100 g / 0.25 mol = 400 g/mol.
For YCl2, we are told that 0.5 moles has a mass of 125 g. So the molar mass is 125 g / 0.5 mol = 250 g/mol.