Calculate the molar mass of the substance – Phosphorus molecule, P4 (Atomic mass of phosphorus = 31)
The Correct Answer and Explanation is:
Correct Answer:
The molar mass of the phosphorus molecule, P₄, is:Molar mass of P4=4×31=124 g/mol\text{Molar mass of P}_4 = 4 \times 31 = 124 \text{ g/mol}Molar mass of P4=4×31=124 g/mol
Explanation:
To calculate the molar mass of any compound or molecule, we first need to know two key pieces of information:
- The chemical formula of the molecule
- The atomic masses of the constituent elements
In this case, the molecule in question is phosphorus, which commonly exists in nature as a tetraphosphorus molecule, written as P₄. This molecular form means that one molecule of phosphorus consists of four atoms of phosphorus chemically bonded together.
The atomic mass of a single phosphorus atom is given as 31 grams per mole. This means that one mole of phosphorus atoms weighs 31 grams. However, since the P₄ molecule contains four phosphorus atoms, we must multiply the atomic mass by 4 to get the total molar mass of the P₄ molecule:Molar mass of P4=4×31=124 grams per mole\text{Molar mass of P}_4 = 4 \times 31 = 124 \text{ grams per mole}Molar mass of P4=4×31=124 grams per mole
This calculation tells us that one mole of P₄ molecules weighs 124 grams. This value is essential in stoichiometry when performing chemical reaction calculations involving phosphorus.
Understanding molar mass allows chemists to convert between the mass of a substance and the number of moles, which is important when determining reactant-product relationships, reaction yields, and reagent quantities.
For example, if a chemist needs 1 mole of P₄ for a reaction, they must weigh out 124 grams of the substance. If they only have 62 grams, then they have 0.5 moles of P₄. This concept ensures that chemical reactions are carried out using precise quantities, leading to correct and predictable outcomes.
