Calculate the percent composition by mass of each element in Al(OH)3
Use at least 3 significant figures.
%Al =
%O =
%H=
%Al = (atomic mass Al/molar mass Al(OH)3) x 100 = ??
The other elements are done the same way.
To calculate the percent composition by mass of each element in Al(OH)3, you need to determine the mass of each element in the compound and then divide it by the molar mass of the compound. Finally, multiply the result by 100 to convert it to a percentage.
1. Determine the molar mass of Al(OH)3:
- The molar mass of aluminum (Al) is 26.98 g/mol.
- The molar mass of oxygen (O) is 16.00 g/mol.
- The molar mass of hydrogen (H) is 1.01 g/mol.
So, the molar mass of Al(OH)3 is:
(26.98 g/mol x 1) + (16.00 g/mol x 3) + (1.01 g/mol x 3) = 78.00 g/mol
2. Calculate the mass of each element in Al(OH)3:
- Aluminum (Al): There is only one Al atom in Al(OH)3, so its mass is 26.98 g/mol.
- Oxygen (O): There are three O atoms in Al(OH)3, so its mass is 16.00 g/mol x 3 = 48.00 g/mol.
- Hydrogen (H): There are three H atoms in Al(OH)3, so its mass is 1.01 g/mol x 3 = 3.03 g/mol.
3. Calculate the percent composition of each element:
- %Al = (mass of Al / molar mass of Al(OH)3) x 100
= (26.98 g / 78.00 g) x 100
= 34.59%
- %O = (mass of O / molar mass of Al(OH)3) x 100
= (48.00 g / 78.00 g) x 100
= 61.54%
- %H = (mass of H / molar mass of Al(OH)3) x 100
= (3.03 g / 78.00 g) x 100
= 3.88%
Therefore, the percent composition by mass of each element in Al(OH)3 is approximately:
%Al = 34.59%
%O = 61.54%
%H = 3.88%