Question

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

Answer 1

Answer: 2.7 kg


Step-by-step 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

Answer 2

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