Answer
160.7g of bromine is needed to react with 18.1 g of aluminum.
Work Step by Step
1- Step one: Apply the law of conservation of mass for the chemical reaction:
m (of aluminum) + m (of bromine) = m (of aluminum bromide)
2- Step two: Replace the mass of aluminum, and mass of aluminum bromide:
27.0 g + m (of bromine) =266.7 g
m (of bromine) = 266.7 g – 27.0 g
m (of bromine) = 239.7 g
3- Step three: using the law of conservation of mass we found that 27 g of aluminum would react with 239.7 g of bromine. Than what would be the mass of bromine that would be needed to react with 18.1 g aluminum? Applying the knowledge of law of conservation of mass, we can write:
27.0 g aluminum react with 239.7 g bromine
18.1 g aluminum react with unknown mass of bromine
4 – Step four: find the mass of bromine using the mathematical rule of three :
Unknown mass of bromine = (18.1 g x 239.7 g) / 27.0 g
Unknown mass of bromine = 4338.6 g2 / 27.0 g
We find that the mass of bromine is 160.7 g.