Answer: C
Explanation:
- The atomic mass of aluminum is 26.98154 g/mol.
- The atomic mass of chlorine is 35.453 g/mol.
So, the formula mass of aluminum chloride is 26.98154+3(35.453)=133.34054 g/mol.
This means that 42.3 grams of aluminum chloride are 42.3/133.34054=0.31723285356426 moles.
From the equation, we know that for every 3 moles of bromine consumed, 2 moles of aluminum chloride are consumed.
This means that (0.31723285356426)(3/2)=0.47584928034639 moles of bromine are needed.
- The atomic mass of one bromine atom is 79.904 g/mol
So, the formula mass of a bromine molecule is 2(79.904)=159.808 g/mol, and thus the answer is (159.808)(0.47584928034639), which is about 76.1 g