Question

If 5 moles of Al2O3 are formed in the reaction " 4 Al + 3 O2 ---> 2 Al2O3 " How many moles of Aluminum (Al) & How many moles of Oxygen (O2) are consumed in the reaction?

Answer 1

We are given the reaction:

4 Al + 3 O₂ → 2 Al₂O₃

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Finding moles of Al reacted:

from which, we can deduce that 4 moles of Al produces 2 moles of Al₂O₃

Ratio between their moles:

Moles of Al / Moles of Al₂O₃

4 / 2 = 2 / 1

so,

Moles of Al / Moles of Al₂O₃ = 2

Moles of Al = 2* Moles of Al₂O₃

we are given that 5 moles of Al₂O₃ are formed, replacing the value:

Moles of Al = 2*5

Moles of Al = 10 moles

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Finding moles of O₂ reacted:

from the given equation, we can also say that 4 moles of Al react with 3 moles of O₂

Moles of Al / Moles of O₂ = 4 / 3

3 * (Moles of Al) = 4* (Moles of O₂)

we know that 10 moles of Al reacted,

3 * (10) = 4 * (moles of O₂)

Moles of O₂ = 30/4

Moles of O₂ = 7.5 moles