Calculate the mass fractions of the elements included in the composition: 1) Aluminum hydroxide Al (OH)

| May 9, 2021 | education

Calculate the mass fractions of the elements included in the composition: 1) Aluminum hydroxide Al (OH) 3 2) copper oxide (2) CuO.

Exercise 1.
Aluminum hydroxide Al (OH) 3.
Let’s write an expression to determine the mass fraction of a substance:
w (email) = (M (email) / M (things)) * 100%.
Let us determine the molar masses of the elements:
M (Al) = 26 g / mol.
M (O) = 16 * 3 = 48 g / mol.
M (H) = 1 * 3 = 3 g / mol.
M (Al (OH) 3) = 26 + 16 * 3 + 1 * 3 = 77 g / mol.
Let’s calculate the mass fraction of elements:
w (Al) = (M (Al) / M (Al (OH) 3)) * 100% = (26/77) * 100% = 33.8%.
w (O) = (M (O) / M (Al (OH) 3)) * 100% = (48/77) * 100% = 62.2%.
w (H) = (M (H) / M (Al (OH) 3)) * 100% = (3/77) * 100% = 4%.

Task 2.
Copper (II) oxide CuO.
Let’s write an expression to determine the mass fraction of a substance:
w (email) = (M (email) / M (things)) * 100%.
Let us determine the molar masses of the elements:
M (Cu) = 63.5 g / mol.
M (O) = 16 g / mol.
M (CuO) = 63.5 + 16 = 79.5 g / mol.
Let’s calculate the mass fraction of elements:
w (Cu) = (M (Cu) / M (CuO)) * 100% = (63.5 / 79.5) * 100% = 79.9%.
w (O) = (M (O) / M (CuO)) * 100% = (16 / 79.5) * 100% = 20.1%.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.