
How can I find the percent composition of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$
Answer
445.8k+ views
Hint: We know that, percentage composition of a compound is the relative mass of each of the constituent elements in 100 parts of it by mass. To calculate percentage composition, first we have to calculate the molecular mass of the given compound. Then, we have to calculate the % of each element present in the compound.
Complete step by step answer:
We have to calculate the molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$.
We know that the atomic mass of oxygen is 16 g/mol, the atomic mass of sulphur is 32 g/mol and the atomic mass of aluminium is 26.98 g/mol.
Molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$=$2 \times $atomic mass of Al+3$ \times $atomic mass of sulphur +12$ \times $atomic mass of oxygen
Molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$=$2 \times 26.98 + 3 \times 32.06 + 12 \times 16 = 53.96 + 96.18 + 192 = 342.14\,{\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$
Now, we have to calculate the percentage of each element.
Let’s start with Aluminium.
% of aluminium (Al)$ = \dfrac{{{\text{Mass}}\,{\text{of}}\,{\text{Al}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of aluminium (Al)$ = \dfrac{{53.96}}{{342.14}} \times 100 = 15.77\% $
Then, we calculate % composition of Sulphur.
% of sulphur (S)$ = \dfrac{{{\text{Mass}}\,{\text{of S}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of Sulphur(S)$ = \dfrac{{96.18}}{{342.14}} \times 100 = 28.11\% $
Then, we calculate % composition of oxygen.
% of oxygen (O)$ = \dfrac{{{\text{Mass}}\,{\text{of O}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of oxygen (O)$ = \dfrac{{192}}{{342.14}} \times 100 = 56.11\% $
Hence,
The percentage composition of Al is 15.77%
The percentage composition of S is 28.11%
The percentage composition of Al is 56.11%
Note: It is to be noted that molecular mass of a compound is calculated by adding the atomic masses of all atoms which constitute the molecules of that compound. Also, if we add the percentage of all the elements of a compound, we will get 100. Percentage composition helps us to know about the percentage of each element making the compound.
Complete step by step answer:
We have to calculate the molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$.
We know that the atomic mass of oxygen is 16 g/mol, the atomic mass of sulphur is 32 g/mol and the atomic mass of aluminium is 26.98 g/mol.
Molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$=$2 \times $atomic mass of Al+3$ \times $atomic mass of sulphur +12$ \times $atomic mass of oxygen
Molecular mass of ${\text{A}}{{\text{l}}_{\text{2}}}{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)_{\text{3}}}$=$2 \times 26.98 + 3 \times 32.06 + 12 \times 16 = 53.96 + 96.18 + 192 = 342.14\,{\text{g}}\,{\text{mo}}{{\text{l}}^{ - 1}}$
Now, we have to calculate the percentage of each element.
Let’s start with Aluminium.
% of aluminium (Al)$ = \dfrac{{{\text{Mass}}\,{\text{of}}\,{\text{Al}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of aluminium (Al)$ = \dfrac{{53.96}}{{342.14}} \times 100 = 15.77\% $
Then, we calculate % composition of Sulphur.
% of sulphur (S)$ = \dfrac{{{\text{Mass}}\,{\text{of S}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of Sulphur(S)$ = \dfrac{{96.18}}{{342.14}} \times 100 = 28.11\% $
Then, we calculate % composition of oxygen.
% of oxygen (O)$ = \dfrac{{{\text{Mass}}\,{\text{of O}}}}
{{{\text{Molecular}}\,{\text{mass}}\,{\text{of}}\,{\text{A}}{{\text{l}}_{\text{2}}}{{\left( {{\text{S}}{{\text{O}}_{\text{4}}}} \right)}_{\text{3}}}}} \times 100$
$ \Rightarrow $% of oxygen (O)$ = \dfrac{{192}}{{342.14}} \times 100 = 56.11\% $
Hence,
The percentage composition of Al is 15.77%
The percentage composition of S is 28.11%
The percentage composition of Al is 56.11%
Note: It is to be noted that molecular mass of a compound is calculated by adding the atomic masses of all atoms which constitute the molecules of that compound. Also, if we add the percentage of all the elements of a compound, we will get 100. Percentage composition helps us to know about the percentage of each element making the compound.
Recently Updated Pages
Master Class 11 Accountancy: Engaging Questions & Answers for Success

Glucose when reduced with HI and red Phosphorus gives class 11 chemistry CBSE

The highest possible oxidation states of Uranium and class 11 chemistry CBSE

Find the value of x if the mode of the following data class 11 maths CBSE

Which of the following can be used in the Friedel Crafts class 11 chemistry CBSE

A sphere of mass 40 kg is attracted by a second sphere class 11 physics CBSE

Trending doubts
Define least count of vernier callipers How do you class 11 physics CBSE

The combining capacity of an element is known as i class 11 chemistry CBSE

Proton was discovered by A Thomson B Rutherford C Chadwick class 11 chemistry CBSE

Find the image of the point 38 about the line x+3y class 11 maths CBSE

Can anyone list 10 advantages and disadvantages of friction

Distinguish between Mitosis and Meiosis class 11 biology CBSE
