Al 2 (SO 4 ) 3 - aluminum sulfate, an inorganic substance from the class of salts. It occurs in the form of crystals or white powder, it is well soluble in water. A chemically active substance that reacts well with many components, therefore it is often used in experiments and problems in chemistry, but to solve them you need to know the molar mass of Al 2 (SO 4 ) 3 .
Indicator calculation
The relative molecular weight of aluminum sulfate is the volume of one single molecule of this substance. Let's consider in more detail.
The indicator is expressed in atomic units of mass (amu). It is easy to calculate using the periodic system of Mendeleev’s elements, knowing the formula of the substance.
To do this, you need to find in the table the elements that make up the substance of interest to us - aluminum, sulfur and oxygen. The relative mass of one aluminum atom is 26.992 amu (rounded to 27), sulfur atom 32,064 (rounded to 32), oxygen atom 15,999 (rounded to 16).
The formula of the aluminum sulfate molecule in the figure below. It shows the composition of the molecule, and how many atoms of each element are involved in the formation of one conditional molecule of matter.
Next, you need to multiply the mass of one aluminum atom by the number of these particles in the Al 2 (SO 4 ) 3 molecule. This number is indicated by the lower index to the right of the aluminum symbol - 2. Multiply 2 by 27, we get 54 amu
Next, repeat the steps with the sulfur atom. The aluminum sulfate molecule contains three particles (SO 4 ), which means three sulfur atoms. We multiply 32 by 3, we get 96 amu
We make the same calculation with oxygen atoms. First, we calculate how many of them are part of the molecule. It contains three particles (SO 4 ), that is, 12 oxygen atoms. We multiply the mass by the number of atoms - 16 by 12, we get 192 amu
The last action is to add the masses of all the constituent parts of the molecule:
54 + 96 + 192 = 342 amu
So, the molecular weight of aluminum sulfate is 342 amu
Next indicator
The molar mass of al2 so4 3 is the volume of one mole of aluminum sulfate. It is very easy to recognize, since it is numerically equal to the molecular weight, but is expressed in other units of measurement - g / mol.
So, the molar mass of al2 so4 3 is 342 g / mol. This value is often required to solve problems.
Molar mass equivalent
To calculate this value, you need to know the equivalence factor. It is defined differently for classes of substances.
Aluminum sulfate belongs to the group of medium salts. For such compounds, the equivalence factor is considered as follows:
- It is necessary to divide the unit by the product of the number of metal atoms and the metal charge.
- Find the product. There are two aluminum metal atoms in the molecule, this can be seen from the formula. The charge of aluminum is constant and equal to three, that is 2 * 3 = 6.
- The equivalence factor of aluminum sulfate salt is 1/6.
To find the molar mass of the equivalent of aluminum sulfate, multiply its molar mass by the equivalence factor:
342 * 1/6 = 57 g / mol.
So, the molar mass of the equivalent of Al2 (SO4) 3 is 57 g / mol.
The calculations are completed, the desired value is determined.