What is the molar mass of barium phosphate? Steps: first derive formula, then calculate molar mass.
The correct answer and explanation is:
Correct Answer:
The molar mass of barium phosphate is 601.93 g/mol.
Step 1: Derive the chemical formula of barium phosphate
Barium (Ba) is a metal that forms a 2+ cation, written as Ba²⁺.
The phosphate ion is a polyatomic ion with the formula PO₄³⁻ and a 3− charge.
To form a neutral compound, balance the charges of barium and phosphate:
- 3 Ba²⁺ gives a total charge of +6
- 2 PO₄³⁻ gives a total charge of -6
So, the chemical formula becomes Ba₃(PO₄)₂.
Step 2: Calculate the molar mass of Ba₃(PO₄)₂
Now add the atomic masses from the periodic table:
- Ba (Barium) = 137.33 g/mol
- P (Phosphorus) = 30.97 g/mol
- O (Oxygen) = 16.00 g/mol
Break down the formula:
- 3 Barium atoms → 3 × 137.33 = 411.99 g/mol
- 2 Phosphorus atoms → 2 × 30.97 = 61.94 g/mol
- 8 Oxygen atoms → 8 × 16.00 = 128.00 g/mol
Total molar mass = 411.99 + 61.94 + 128.00 = 601.93 g/mol
Explanation (300 words):
To determine the molar mass of a compound, it is essential to start by writing its correct chemical formula. Barium phosphate is an ionic compound made of barium ions and phosphate ions. Barium forms a +2 charge because it loses two electrons when forming ions. The phosphate ion is a stable polyatomic ion with a -3 charge. Since the charges must balance to form a neutral compound, three Ba²⁺ ions (total +6) are needed to balance with two PO₄³⁻ ions (total -6). Therefore, the formula becomes Ba₃(PO₄)₂.
After establishing the formula, calculating the molar mass involves summing the individual atomic masses for each atom in the compound. For barium phosphate, this includes three barium atoms, two phosphorus atoms, and eight oxygen atoms. Each atomic mass is taken from the periodic table. Multiplying each atomic mass by the number of atoms of that element gives the total mass contribution of each element. The sum of all these gives the total molar mass of the compound.
Molar mass is expressed in grams per mole and represents the mass of one mole of a given substance. It is a crucial concept in chemistry because it links the mass of a substance to the number of particles it contains. This connection allows for conversions between grams and moles, which is essential for stoichiometric calculations in chemical reactions. For barium phosphate, knowing the molar mass helps chemists measure the right amount needed for reactions involving phosphate compounds.