Aluminum metal reacts with bromine 2

Aluminum metal reacts with bromine, a red-brown liquid with a noxious odor. The reaction is vigorous and produces aluminum bromide, a white crystalline substance. A sample of 27.0 g of aluminum yields 266.7 g of aluminum bromide. How many grams of bromine react with 15.0 g of aluminum?

Solution:

We will use the law of conservation of mass to figure out how many grams of bromine reacted with the aluminum. We can write the following:

Mass of aluminum + mass of bromine = mass of aluminum bromide

Thus we can write:

27.0g + m_{Br} = 266.7g

m_{Br}=239.7g

To figure out how many grams of bromine reacts with 15.0 g of aluminum, we can write the following equation.

15.0g + x=m_{AlBr_3} (Where x is the mass of bromine that reacts with the aluminum)

Now, we will write a proportion that relates the reacting materials.

\frac{m_{Al}}{m_{Br}}=\frac{27.0g}{239.7g}=\frac{15.0g}{x}

x=133.1g

This question can be found in General Chemistry, 9th edition, chapter 1, question 1.40