Question

How many grams of aluminum burned if $$200.0g$$ of aluminum oxide formed?

Answer 1

Hint: If we type the balanced equation between al giving $$A{l}_2{O}_3$$,
The quantity of aluminum atoms is two and the quantity of oxygen atoms is three. As we recognize the atomic masses of aluminum as $$26.9815386grams$$ per mole and oxygen as $$16.9994grams$$ per mole.

Complete step by step answer:
Answer type 1st –
Balanced equation
$$4Al\left(s\right)+3O_2\left(g\right)\stackrel{\mathrm{\Delta }}{\to }2A{l}_2{O}_3$$
There are three steps compulsory to answer this question.
1. Define moles of $$A{l}_2{O}_3$$ by dividing the specified mass by its molar mass $$\left(101.960g/mol\right).$$I select to do this by means of multiplying by the reciprocal of the molar mass (mol/g).
2. Define moles of $$Al$$ by multiplying moles $$A{l}_2{O}_3$$ by the mole ratio between $$Al$$and $$A{l}_2{O}_3$$ as of the balanced equation, with $$Al$$ in the numerator.
3.Define mass of $$Al$$ by multiplying moles $$Al$$ by this one molar mass $$\left(26.982g/mol\right).$$

$$1.962molA{l}_2{O}_3\times {\displaystyle \frac{4molAl}{2molA{l}_2{O}_3}}=3.924molAl$$
$$3.924molAl\times {\displaystyle \frac{26.982gAl}{1molAl}}=105.9g$$(round to four significant figures)
We can association all steps into one equation:
$$200.0gA{l}_2{O}_3\times {\displaystyle \frac{1molA{l}_2{O}_3}{101.960gA{l}_2{O}_3}}\times {\displaystyle \frac{4molAl}{2molA{l}_2{O}_3}}\times {\displaystyle \frac{26.982gAl}{1molAl}}=105.9g$$
(round to four significant figures)
$$105.9g$$$$Al$$were burned in excess$$O_2$$ to produce $$200.0g$$ $$A{l}_2{O}_3$$

Answer type 2nd -The molecular mass of Aluminum Oxide is nearly $$102grams$$per mole.
$$2\times Al=2\times 27=54$$
$$3\times O=3\times 16=48$$
$$54+48=102$$
${\displaystyle \frac{200}{102}}=1.96\text{moles}$
There are two atoms of Aluminum in one mole and every atom has a mass of nearly $$27grams$$ so Mass of $$Al=1.96\times 2\times 27=106grams$$

Note: Do not be confused with the confrontations alumina and aluminum oxide. Mutually are the same. Alumia is the Communal name given to aluminum oxide. Molecular formula of aluminum oxide is $$A{l}_2{O}_3$$.Generally Alumina is presented in nature in the form of bauxite. Bauxite is an ore that is mined as a topsoil in several tropical and subtropical regions. In $$1887$$ a process exposed called the Bayer process. It is the primary procedure by which alumina can be taken out from bauxite.