So, you just finished a chemistry experiment. You followed every step perfectly… but your final product was less than expected. What happened?
That’s where percentage yield comes in!
This nifty calculation helps you compare how much product you actually made versus how much you should have made in a perfect world. Let’s dive into how to calculate it—with easy steps and fun examples.
Table of Contents
🔍 What is Percentage Yield?
Percentage yield shows how efficient a chemical reaction was by comparing the amount of product you got to the amount you were supposed to get.
Think of it like baking cookies:
- Theoretical yield = the number of cookies the recipe says you’ll get.
- Actual yield = the number of cookies you actually baked.
- Percentage yield = how close you got to cookie perfection. 🍪
📐 The Percentage Yield Formula
Percentage Yield = (Actual Yield/Theoretical Yield) × 100
Where:
- Actual yield = what you measured in the lab (usually in grams or moles)
- Theoretical yield = what you should have gotten based on stoichiometry
- Multiply by 100 to get a percentage
🧠 Example 1: Chemistry Edition
Let’s say you did a reaction that should produce 10 grams of product (theoretical yield), but you only got 8 grams (actual yield).
Percentage Yield = (8/10) × 100 = 80%
So your percentage yield is 80%. Not bad!
🍪 Example 2: Cookie Analogy
Your cookie recipe says you’ll make 24 cookies. You drop some dough, and your dog eats one. In the end, you only get 18 cookies.
Percentage Yield = (18/24) × 100 = 75%
So your cookie yield is 75%. Your dog owes you.
🛠️ Common Reasons for Lower Yields
- Incomplete reactions – not everything reacted
- Side reactions – uninvited chemistry
- Loss during transfer – stuff got stuck to beakers or spilled
- Purification loss – filtering or drying may remove some product
🏆 What’s a “Good” Yield?
- 90–100% – Excellent!
- 80–89% – Pretty good
- 50–79% – Okay, could improve
- Below 50% – Something might have gone wrong
In real-life lab work, especially in organic chemistry, even 50-70% is considered decent, depending on the reaction.
✅ Recap
- Percentage yield = (Actual ÷ Theoretical) × 100
- It tells you how efficient your reaction was
- It’s normal to get less than 100%—chemistry is messy!
🚀 Final Thought
Whether you’re making molecules or muffins, percentage yield helps you figure out how well things went. It’s a great way to track your progress and spot room for improvement.