calculate the formula mass for BaSO4.
The Correct Answer and Explanation is:
To calculate the formula mass of barium sulfate (BaSO₄), we add the atomic masses of all the atoms in its chemical formula:
Step-by-step calculation:
The formula of barium sulfate is BaSO₄, which contains:
- 1 atom of barium (Ba)
- 1 atom of sulfur (S)
- 4 atoms of oxygen (O)
We use the atomic masses from the periodic table:
- Atomic mass of Ba = 137.33 g/mol
- Atomic mass of S = 32.07 g/mol
- Atomic mass of O = 16.00 g/mol
Now, calculate:
- Barium: 1 × 137.33 = 137.33
- Sulfur: 1 × 32.07 = 32.07
- Oxygen: 4 × 16.00 = 64.00
Now, add all the parts:
Formula mass of BaSO₄ = 137.33 + 32.07 + 64.00 = 233.40 g/mol
Explanation
The formula mass of a compound is the sum of the atomic masses of all the atoms shown in its chemical formula. It is used to describe the mass of a single unit of an ionic compound. In this case, we are calculating the formula mass of barium sulfate (BaSO₄), which is an ionic compound made up of barium ions (Ba²⁺) and sulfate ions (SO₄²⁻).
To find the total mass, we identify each type of atom in the formula and how many of each there are. BaSO₄ contains one barium atom, one sulfur atom, and four oxygen atoms. Each element has a specific atomic mass based on its number of protons and neutrons. These masses are listed in the periodic table.
Using these values, we multiply the atomic mass of each element by the number of times it appears in the compound. For example, oxygen appears four times in BaSO₄, so we multiply the atomic mass of oxygen (16.00) by 4. After finding the individual contributions, we add them to get the total.
Understanding formula mass helps in many chemistry calculations, including determining the amount of substance in moles, calculating percent composition, and converting between grams and moles. For barium sulfate, the formula mass is 233.40 g/mol, meaning one mole of BaSO₄ weighs 233.40 grams. This value is useful in laboratory settings, especially when preparing solutions or analyzing chemical reactions involving BaSO₄.
