• Quick Bite: Think of enthalpy like the energy in your piggy bank. You don’t care about every single coin that goes in or out, just the final balance!
• What is it? Enthalpy is the total energy in a system.
• How's it change? The change in enthalpy (ΔH) is simply the difference between the starting and ending energy amounts.

Real-World Example: It's like monitoring your phone's battery life! Whether you play games or watch videos, you care about the battery level before you started and after you ended.

• No matter how you get from start to finish in a chemical reaction, the total enthalpy change stays the SAME.

Real-World Example: Imagine driving from home to school. You can take the highway or a scenic route. No matter which route you take, you'll still reach school, right? The same goes for reactions and their enthalpy changes!

• Quick Formula: ΔHr ⦵ = (Σ ΔH of combustion of reactants) - (Σ ΔH of combustion of products).
• What's it mean?: The overall standard enthalpy change for a reaction can be calculated using the enthalpy changes when things burn (combustion).
• Reminder: This formula is a superstar application of Hess’s Law!

Real-World Example: It's like comparing the calories burnt from different workouts. Let's say jogging burns 300 calories, and yoga burns 150. If you do jogging (reactant) but skip yoga (product), the net burn is 150 calories!