Stoikiometri (2) | Konsep Mol | Kimia Kelas 10

Introduction

In this tutorial, we will explore the concept of stoichiometry, specifically focusing on the mole concept as discussed in a Class 10 chemistry video. Understanding the mole is essential for grasping the relationships between quantities in chemical reactions, which is fundamental in chemistry studies.

Step 1: Understanding the Mole Concept

• The mole (mol) is a basic unit in chemistry that measures the amount of substance.
• One mole of any substance contains approximately (6.022 \times 10^{23}) particles, a number known as Avogadro's number.
• This relationship allows chemists to convert between the number of particles (atoms, molecules, ions) and the amount of substance in moles.

Practical Advice

• Use Avogadro's number to calculate the number of particles from moles:
  • Formula: Number of particles = Moles × (6.022 \times 10^{23})

Step 2: Relationship Between Moles and Mass

• The mass of a substance can be calculated using its molar mass.
• Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol).

Calculation Steps

1. Determine the molar mass of the substance (sum of the atomic masses of all atoms in the molecular formula).
2. Use the formula:
   • Mass (g) = Moles × Molar Mass (g/mol)

Example

• For water (H₂O), the molar mass is approximately 18 g/mol (2×1 for H + 16 for O).
• If you have 2 moles of water:
  • Mass = 2 moles × 18 g/mol = 36 grams

Step 3: Volume Relationships at Standard Temperature and Pressure (STP)

• At STP (0°C and 1 atm), one mole of an ideal gas occupies 22.4 liters.

Calculation Steps

1. Use the formula:
   • Volume (L) = Moles × 22.4 L/mol
2. Example:
   • If you have 3 moles of an ideal gas:
     • Volume = 3 moles × 22.4 L/mol = 67.2 liters

Step 4: Volume Relationships Under Non-STP Conditions

• When dealing with gases at conditions other than STP, the Ideal Gas Law can be applied:
  • Ideal Gas Law Formula: PV = nRT
    • P = pressure (atm)
    • V = volume (L)
    • n = number of moles
    • R = ideal gas constant (0.0821 L·atm/(K·mol))
    • T = temperature (K)

Practical Applications

1. Rearranging the Ideal Gas Law to find volume:
   • V = nRT/P
2. Example:
   • If you have 1 mole of gas at 2 atm pressure and 300 K:
     • V = (1 mol × 0.0821 L·atm/(K·mol) × 300 K) / 2 atm
     • Calculate to find the volume.

Conclusion

This tutorial covered the fundamental concepts of the mole in stoichiometry, including its relationship with particles, mass, and volume. Understanding these relationships is crucial for solving problems in chemistry. For further learning, practice calculating moles, mass, and volume using various substances and conditions to strengthen your understanding. Happy studying!