A chemistry has 14.5 g of Al and 7.5 g of #O_2#. What would the excess be for the following reaction: #4Al + 3O_2 -> 2Al_2O_3#?

Answer 1

Al is in limiting
#O_2# is in excess

The number of moles must be determined and then divided by the coefficient in order to check excess and limiting reactants. To make the equations shorter, let's say that:

#n="number of moles"# #m="mass"# #M="molar mass"#

We must apply the following formula to determine the number of moles:

#n=m/M#
The mass is given in the question: #m_"Al"=14.5g# #m_"Oxygen gas"=7.5g#
Molar mass of Al and Oxygen can be found in periodic table, #M_"Al"≈27g/mol# #M_"Oxygen gas"= 2*M_"Oxygen atom"≈2* 16=32 "g/mol"# (since oxygen gas (#O_2#) has two atoms of Oxygen (O))

Now enter these values in the formula for the number of moles: For Al

#n=m/M=14.5/27=0.537 mols#
For #O_2#
#n=7.5/32=0.234 mols#

All that's left to do is divide the moles by their corresponding coefficients and compare the results.

For Al

#n/4=0.537/4=0.134#
For #O_2#
#n/2=0.234/2=0.17#

The larger of the two reactants will be in excess, and the smaller of the two will be in limiting.

#"the value of Al (0.134)"< "the value of O_2 (0.17)"#
Therefore, Al is in limiting (there is less of it and thus it is limiting the reaction) and #O_2# is in excess.

I hope this is helpful. :)

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Answer 2

In order to identify the excess reactant, we must first determine the amount of Al and O2 required for the reaction using the stoichiometry of the equation. Next, we compare the actual amounts of Al and O2 provided to determine which is in excess. 1. Calculate the moles of Al and O2 provided: - Moles of Al = mass of Al / molar mass of Al

  • Moles of O2 = mass of O2 / molar mass of O2
  1. Apply the reaction's stoichiometry to ascertain the theoretical amount of Al and O2 required: - Based on the balanced equation, 4 moles of Al react with 3 moles of O2 to produce 2 moles of Al2O3. 3. Identify the limiting reactant: - Compare the actual moles of Al and O2 to the theoretical moles needed for the reaction. The reactant that produces fewer moles of Al2O3 is the limiting reactant.
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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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