Excess fluorine, F2(g), reacts at 150°C with bromine, Br2(g), to give a compound BrFn. If 423 mL Br2(g) at 150°C and 748 mmHg produced 4.20 g BrFn, what is n? Predict the shape of this molecule using the VSEPR model.

Answer 1

Use PV = nRT to calculate n for Br2 and convert to grams. Subtract from 4.20 to find grams fluorine.
Then convert g bromine to moles. moles = g/molar mass.
convert g fluorine to moles same way.

Now find the ratio of the elements to each other with the lowest number being 1.00. The easy way to do that is to divide the smaller number by itself (thereby getting 1.000000 for that one) then divide the other number by the same small number. Round to whole numbers to find the empirical formula.
After determining the formula, write a Lewis electron dot structure to deduce the VSEPR shape. Post your work if you get stuck.