Question

Use the reaction given below to solve the problem that follows: Calculate the mass in grams of aluminum metal required to react with 115 g of oxygen gas.

4 Al + 3 O2 ——> 2 Al2O3

Answer: _____ grams Al

Answer 1

129.4g

Step-by-step explanation:

Reaction equation":

4Al + 3O₂ → 2Al₂O₃

Given mass of oxygen = 115g

Unknown:

mass of aluminum metal that reacted;'

Solution:

We need to convert the given mass of O₂ to mole;

Number of moles =
`(mass)/(molar mass)`

Molar mass of O₂ = 2(16) = 32g/mol

Number of moles =
`(115)/(32)` = 3.6mol

From the balanced reaction equation:

3 moles of O₂ reacted with 4 mole of Al

3.6 moles of O₂ will react with
`(3.6 x 4)/(3)` = 4.8mol

Mass of Al = number of moles x molar mass

Mass of Al = 4.8 x 27 = 129.4g