2. Catalyst Calculate the number of grams of carbon dioxide produced when 1.2 x 10 24 particles of oxygen gas (O 2 ) are reacted. 2 C 2 H 2 + 5 O 2 ---> 4 CO 2 + 2 H 2 O End

3. Test Next Monday/Tuesday!

4. Lecture 4.6 – Percent Yield

5. Today’s Learning Targets LT 4.9 – I can hypothesize and calculate the percent yield for a given chemical reaction.

6. What is percent yield?

7. I. Percent Yield Stoichiometry tells us what should happen for a reaction. This is the theoretical yield. We predict using stoichiometry conversions The amount that a reaction actual produces is known as the actual yield.

8. How do we calculate percent yield?

9. I. Calculating the Percent Yield Percent yield can be calculated by the equation: Calculate the theoretical yield using stoichiometry. Often, you experiment to obtain the actual yield.

10. Class Example I perform the following reaction: 2H 2 + O 2  2H 2 O and I predict that I will produce 18 g of H 2 O. If I actually produce 16 g of H 2 O, then what is my percent yield?

11. Class Example I perform the following reaction: 4 KI + K 4 (CrO 4 ) 2  2 I 2 + 2 K 2 O + K 4 (CrO 3 ) 2 I react 332 g of KI with excess K 4 (CrO 4 ) 2. If I actually produce 228.6 g of I 2, what is my percent yield for the reaction?

12. Percent Yield Lab Please read through the lab handout that you picked up when you entered the classroom. Note areas of confusion. Once finished discuss with your table what each person at your table will be doing once the lab has begun.

13. Lab Work Time

14. Lab Debrief Make sure to complete the calculations and post-lab questions before next Thursday/Friday. Where do you think error was introduced in this lab? What do you think were sources of error for this lab? How did it contribute to your percent yield?

15. What does our percent yield mean?

16. I. What Percent Yield Means Percent yield is often lower than 100% because of error 2 types of error: – Human error – Mistakes that we make during an experiment – Experiment Design Error – There are often error associated with the way that we design an experiment Every experiment has sources of error

17. SUMMARIZE

19. Closing Time Lab Report Discussion due Review Packet worth 5 extra credit point on exam grade!