Answer:
621.41 grams
Step-by-step explanation:
First of all, to find the mass. You have to use the molar mass of AlBr3 to convert from moles to mass.
Second of all, find the molar mass of AlBr3.
Al = 27.0 amu
Br = 79.9 amu
They are 3 bromine atoms and 1 aluminum atom.
So you do this
27.0 + 79.9(3) = 266.7
The molar mass is 266.7 g/mol
Third of all, use dimensional analysis to show your work.
2.33 moles of AlBr3 * 266.7 g/mol / 1 mol
Moles cancel out.
2.33 x 266.7 = 621.411
Your teacher though said to round digits after the decimal point instead of using sig figs.
621.411 rounds to 621.41
So the final answer is 621.41 grams(don't forger the units).
The substance formula is just AlBr3.
That's all.
Hope it helped!