What Is The Mass Of 3.81 Mol Of Ph3

Determining the Mass of 3.81 mol of PH₃: A Comprehensive Guide

This article will guide you through the process of calculating the mass of 3.81 moles of phosphine (PH₃). We'll cover the fundamental concepts, step-by-step calculations, and delve into the underlying chemistry involved. Understanding molar mass and its application is crucial in various chemical calculations, and this example provides a practical illustration. This comprehensive guide will equip you with the knowledge to tackle similar problems confidently.

Understanding Molar Mass

Before we begin the calculation, let's solidify our understanding of molar mass. Molar mass is the mass of one mole of a substance. It's expressed in grams per mole (g/mol). The molar mass of an element is numerically equal to its atomic weight found on the periodic table. For compounds, the molar mass is the sum of the molar masses of all the atoms in the chemical formula.

For PH₃ (phosphine), we need to consider the molar masses of phosphorus (P) and hydrogen (H). According to the periodic table:

• The atomic weight of Phosphorus (P) is approximately 30.97 g/mol.
• The atomic weight of Hydrogen (H) is approximately 1.01 g/mol.

Therefore, the molar mass of PH₃ is calculated as follows:

Molar mass of PH₃ = (1 × molar mass of P) + (3 × molar mass of H) = (1 × 30.97 g/mol) + (3 × 1.01 g/mol) = 33.97 g/mol

Step-by-Step Calculation: Mass of 3.81 mol of PH₃

Now that we know the molar mass of PH₃, we can calculate the mass of 3.81 moles. We will use the following formula:

Mass (in grams) = Number of moles × Molar mass

1. Identify the known values:

   • Number of moles = 3.81 mol
   • Molar mass of PH₃ = 33.97 g/mol

2. Substitute the values into the formula:

   Mass = 3.81 mol × 33.97 g/mol

3. Perform the calculation:

   Mass = 129.46 g (approximately)

Therefore, the mass of 3.81 moles of PH₃ is approximately 129.46 grams.

Understanding the Significance of Avogadro's Number

The concept of a mole is intrinsically linked to Avogadro's number, which is approximately 6.022 x 10²³ particles (atoms, molecules, ions, etc.) per mole. This means that 3.81 moles of PH₃ contains 3.81 x (6.022 x 10²³) molecules of PH₃. This incredibly large number highlights the microscopic scale at which chemical reactions occur and the usefulness of the mole as a unit to manage such large quantities.

Safety Precautions when Handling PH₃

Phosphine (PH₃) is a highly toxic and flammable gas. It's crucial to emphasize safety precautions when handling this compound. Direct contact should be strictly avoided, and appropriate personal protective equipment (PPE), including respirators and gloves, must be used. The work area should be well-ventilated to minimize exposure risks. Always consult the Safety Data Sheet (SDS) for PH₃ before handling it to understand potential hazards and necessary safety procedures.

Applications of PH₃ and its Compounds

While PH₃ itself is toxic and has limited direct applications, its derivatives find use in various fields:

• Semiconductor Industry: Phosphine is used in the production of certain semiconductors. The controlled introduction of phosphorus into silicon or other semiconductors alters their electrical properties.
• Organophosphorus Chemistry: Phosphine serves as a precursor in the synthesis of numerous organophosphorus compounds. These compounds have diverse applications in agriculture (pesticides), medicine (drugs), and materials science (flame retardants).
• Research and Analytical Chemistry: In analytical chemistry and research settings, PH₃ might be used in specific experiments and analyses.

Further Exploration: Calculations Involving Different Compounds

The principles discussed in this article regarding molar mass and mole calculations can be extended to other compounds. By understanding the chemical formula and using the periodic table to determine the molar mass, one can calculate the mass, number of moles, or number of molecules for any given substance.

For instance, let's consider the calculation for a different compound:

Example: What is the mass of 0.5 moles of H₂O (water)?

1. Determine the molar mass of H₂O:

   Molar mass of H₂O = (2 × 1.01 g/mol) + (1 × 16.00 g/mol) = 18.02 g/mol

2. Use the formula:

   Mass = Number of moles × Molar mass = 0.5 mol × 18.02 g/mol = 9.01 g

Thus, 0.5 moles of water has a mass of approximately 9.01 grams.

Frequently Asked Questions (FAQ)

Q1: What is the difference between molar mass and molecular weight?

A1: The terms molar mass and molecular weight are often used interchangeably. However, molar mass is technically the mass of one mole of a substance, expressed in grams per mole (g/mol), while molecular weight is the mass of a single molecule, usually expressed in atomic mass units (amu). They are numerically equivalent, but the units differ.

Q2: Can I use this calculation for other gases like methane (CH₄)?

A2: Absolutely! The same principles apply to calculating the mass of any compound given its number of moles. You would simply need to calculate the molar mass of methane (CH₄) using the atomic weights from the periodic table and then apply the formula: Mass = Number of moles × Molar mass.

Q3: What if I have the mass and need to find the number of moles?

A3: You can rearrange the formula to solve for the number of moles: Number of moles = Mass / Molar mass.

Q4: Why is Avogadro's number important in this calculation?

A4: Avogadro's number provides the link between the macroscopic world (grams) and the microscopic world (molecules). It allows us to relate the number of moles to the actual number of molecules present in a sample. While not directly used in the mass calculation, it’s a crucial concept underpinning the mole concept itself.

Conclusion

Calculating the mass of 3.81 moles of PH₃ involves understanding the concept of molar mass and applying a simple formula. This calculation, along with the discussion of Avogadro's number and safety precautions, provides a comprehensive understanding of the topic. The principles discussed are widely applicable across various chemical calculations and serve as a strong foundation for further explorations in chemistry. Remember to always prioritize safety when handling chemicals, especially those with hazardous properties like PH₃. This article serves as a stepping stone for exploring more complex stoichiometric calculations and solidifying your understanding of fundamental chemical principles.