Question

What mass of aluminum is produced by the decomposition of 5.0 kg al2o3?

Answer 1

The  mass for  of aluminum that is produced  by  the decomposition  of  5.0 Kg Al2O3 is 2647 g or 2.647  Kg

          calculation
  Write  the equation for decomposition  of Al2O3

Al2O3 = 2Al  + 3 O2

find the  moles  of  Al2O3 =  mass/molar mass

convert  5 Kg  to g   = 5 x1000 = 5000 grams
molar mass of  Al2O3 =  27 x2 + 16 x3  = 102 g/mol

 moles =5000 g/  102 g/mol = 49.0196 moles

by use  of mole ratio between Al2O3 to  Al  which is 1:2  the moles of Al = 49.0196 x2 =98.0392  moles


mass of  Al = moles x molar  mass

= 98.0392 moles x  27g/mol = 2647  grams  or 2647/1000 = 2.647 Kg

Answer 2

Answer: 2.7 kg


Explanation:


1) Find the molar mass of Al₂O₃, using the atomic masses of Al and O:


2x27.0g/mol + 3x16.0g/mol = 102.0 g/mol


2) Find the ratio of Al to Al₂O₃:


2x27.0 / 102.0 = 54.0/102.0 = 27.0/51.0 = 9.0/17.0


3) Use proportionality:

9.0 Kg Al / 17.0 kg Al₂O₃ = x / 5.0 kg


⇒ x = 5.0kg Al₂O₃ x (9.0 kg Al/ 17.0 Kg) Al₂O₃

x = 2.65 kg = 2.7 Kg


Al = 2.7 kg Al