Question

Calculate the percentage by mass of the Aluminium in Al2 O3 (mass no. Al=23 O=16)​

Answer 1

Answer:

The percentage by mass of Al in Al₂O₃ is 52.94 %

Explanation:

molar mass of Al = 27 g/mol

molar mass of O = 16 g/mol

molar mass of Al₂O₃ = 2×27 + 3×16

⇒                                = 102 g/mol.

percentage composition by mass for a compound is given by,

        $\%\; composition =\frac{molar\;mass\;of\; element\times number\;of\;element}{molar\;mass\;of\;compound} \times 100$

the percentage by mass of Al in the compound Al₂O₃ is

                        $\%Al = \frac{27\times2 }{102} \times 100=52.94\%$

Hence, the required answer is 52.94 %

note: mass no. of Al = 27