1. Chemical reactions tutorial Let’s get started!!

2. Goals In this tutorial, you will learn… • How to recognize 3 of the 5 types of reactions • Predict the products of reactions when only given the reactants

3. What are the 5 types of reactions?

4. Which 3 will be we learning about??

5. SYNTHESIS

6. Synthesis • Two or more reactants combine to form… ONE PRODUCT!! AB A + B 

7. Synthesis Continued Mg + O2 MgO Two reactants form one product 2 2 BUT WAIT!! Don’t forget about everything you have already learned! Is your equation balanced??

8. Predicting products Before we keep going… lets learn a few things about predicting products

9. Predicting products • Here are a few important things to remember when predicting products: • The compounds form must be neutral ionic compounds (which means you’ll be paying attention to their charges) • You do NOT carry subscripts from the reactants to the products. • You always balance your equation LAST

10. Let’s go back to that synthesis example • Remember the reaction: Mg + O2 Helpful hint for later…why is oxygen O2 and not just O? Click to find out why

11. Why O2?? Oxygen is a diatomic molecule, which means when oxygen is by itself it must be O2. Remember that this DOES NOT mean that oxygen is O2 in compounds, only by itself! • What are the other diatomic elements? (hint: remember the heavenly 7! F2 H2 Br2 N2 I2 Cl2 O2 Go back

12. Now to predict the products… Mg + O2 • Remember A + B  AB so Mg + O2 will make a compound with magnesium and oxygen. What does a compound with magnesium and oxygen look like??

13. A compound with magnesium and oxygen… Magnesium is a metal, oxygen is a nonmetal so we must be forming an IONIC compound. What’s the charge of Mg? What’s the charge of O? O 2- Mg 2+

14. So what’s the compound? Mg2+ O2- Pick… MgO2 MgO Mg2O2

15. Nope! MgO2 +2 + 2(-2) DOES NOT EQUAL ZERO Try again!

16. Nope! Mg2O2 2(+2) + 2(-2) = 0 But remember ionic compounds need to be in the simplest form Try again!

17. Yes! Very good! • MgO is a neutral, correct ionic compound so our formula is Mg + O2 MgO • Finally, balance the equation to satisfy the law of conservation of mass… 2Mg + O2 2MgO

18. So remember… • When predicting products: • Make correct ionic compounds • THEN balance Let’s move on to the rest of the reaction types…

19. Decomposition

20. Decomposition ONE REACTANT… forms two or more products A + B AB 

21. Decomposition Continued The electrolysis of water is when water decomposes into hydrogen and oxygen gas as shown below: 2H2O  2H2 + O2

22. Predicting products and decomposition • Lets use that same reaction. What if we were not already given the products, how would we predict them? H2O  ?? Water is made of hydrogen and oxygen, so will my products just be H and O?

23. No! • Remember, H and O are both diatomic elements. H2O  H2 + O2 But wait….something is still missing….

24. Balance! • Don’t forget to balance your equation after you make your products! Your final answer should look like this: 2H2O  2H2 + O2

25. You try one… • What is the correct reaction for the decomposition of sodium chloride, NaCl? NaCl Na + Cl 2NaCl  Na2 + Cl2 2NaCl  2Na + Cl2

26. Nope! NaCl Na + Cl • Don’t forget that chlorine is a diatomic element, so it must be Cl2 Try again!

27. Nope! 2NaCl  Na2 + Cl2 • Although this reaction is correctly balanced, sodium is NOT a diatomic element Try again!

28. Yes! Very good! 2NaCl  2Na + Cl2 • This is a correct reaction for the decomposition of sodium chloride. Ready for the last type of reaction?

29. Combustion

30. Combustion • Combustion is the burning of hydrocarbons. Hydrocarbon?? What’s that?? Click to find out! • When a hydrocarbon reacts with oxygen (O2), the products are ALWAYS….. Yes,ALWAYS… Carbon dioxide and water CO2 + H2O

31. Hydrocarbons • A hydrocarbon is an organic molecule made up of hydrogen and carbon. Remember when we learned about these when we talked about organic chemistry?? C20H42 CH4 C6H10

32. Combustion Cont… • Since the products of a combustion reaction are always CO2 and H2O, the hardest part about combustion reactions is balancing them • CH4 + O2 CO2 + H2O Balance this equation…

33. Combustion Cont. • CH4 + O2 CO2 + 2H2O • Be aware… this reaction was pretty easy to balance, some of the combustion reactions get pretty complicated! Like this one… • 4C3H9 + 21O2 12CO2 + 18H2O

34. Ready for your quiz?? Yes! Not quite, review the types of reactions with me…

35. Review • Synthesis reactions: two or more reactants combine to form ONE product A + B  AB • Decomposition reactions: ONE reactant breaks down into two or moreproducts • AB A + B • Combustion reactions: a hydrocarbon reacts with oxygen to produce carbon dioxide and water. • Hydrocarbon + O2 CO2 + H2O Ok, now I’m ready for the quiz!

36. Quiz Question 1/5 • Which of the following is a decomposition reaction? 2Fe + O2 2FeO Na + AgCl Ag + NaCl Na2S  2Na + S

37. Nope! 2Fe + O2 2FeO • This is two reactants forming ONE product which is an example of a synthesis reaction Try again!

38. Nope! Na + AgCl Ag + NaCl • This reaction does not just form one product. This reaction is an example of a single replacement reaction which we will learn about later. Try again!

39. Yes! Very good! Na2S  2Na + S • This reaction is ONE reactant breaking down into two or more products, which is an example of a decomposition reaction. Back to the question! Next question!

40. Quiz Question 2/5 • How can you recognize a combustion reaction? A combustion reaction is the only reaction always has at least two reactants and two products. One of the reactants is always oxygen gas. A combustion reaction always has a hydrocarbon reacting with oxygen to produce carbon dioxide and water. A combustion reaction always has a hydrocarbon reacting with nitrogen, which is a very explosive reaction.

41. Nope! A combustion reaction is the only reaction always has at least two reactants and two products. One of the reactants is always oxygen gas. • We will learn about other reactions that can have more than one product and more than one reactant. This is NOT the way to identify a combustion reaction. Try again!

42. Nope! A combustion reaction always has a hydrocarbon reacting with nitrogen, which is a very explosive reaction. • Although combustion reactions are typically explosive, it is not because they react with nitrogen. Try again!

43. Yes! Very good! A combustion reaction always has a hydrocarbon reacting with oxygen to produce carbon dioxide and water. • This is how we identify a combustion reaction Back to the question! Next question!

44. Quiz Question 3/5 • Pick correct bubble that finishes the reaction below. K + Cl2 ?? K + Cl2 KCl 2K + Cl2 2KCl K + Cl2 KCl2

45. Nope! K + Cl2 KCl2 • Remember to not carry subscripts over to your products. K has a +1 charge and Cl has a -1 charge so the product of KCl2 is not neutral and cannot be correct. Try again!

46. Almost! But not quite… K + Cl2 KCl • Although this product is correct, the equation is not balanced! Try again!

47. Yes! Very good! 2K + Cl2 2KCl • The products are correct and the reaction is balanced! Great job! Back to the question! Next question!

48. Quiz Question 4/5 • Pick correct rectangle that finishes the reaction below. C2H8 + O2  ?? C2H8 + O2 CO2 + H2O C2H8 + 4O2 2CO2 + 4H2O C2H8 + O2 C2H8O2

49. Almost, but not quite… C2H8 + O2 CO2 + H2O • Great job predicting the products, but…. don’t forget to balance!! Try again!

50. Nope! C2H8 + O2 C2H8O2 • Remember that combustion reactions always have carbon dioxide and water as products Try again!