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?
Synthesis
Decomposition
Combustion
Single replacement
Double replacement

4. Which 3 will be we learning about??
Synthesis
Decomposition
Combustion

5. SYNTHESIS

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

7. Two reactants form one product
Synthesis Continued 2 2
Mg O2  MgO
Two reactants form one product
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. Mg + O2  MgO 2Mg + O2  2MgO 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. But wait….something is still missing….
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. Hydrocarbon?? What’s that?? Click to find out!
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
CO 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. Balance this equation…
Combustion Cont…
Since the products of a combustion reaction are always CO2 and H2O, the hardest part about combustion reactions is balancing them
CH O2  CO H2O
Balance this equation…

33. CH4 + O2  CO2 + 2H2O Combustion Cont. 4C3H9 + 21O2  12CO2 + 18H2O
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. Not quite, review the types of reactions with me…
Ready for your quiz??
Yes!
Not quite, review the types of reactions with me…

35. Ok, now I’m ready for the quiz!
Review
Synthesis reactions: two or more reactants combine to form ONE product
A + B  AB
Decomposition reactions: ONE reactant breaks down into two or more products
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! This is how we identify a combustion reaction
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.
C2H 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!

51. Yes! Very good!
C2H8 + 4O2 2CO2 + 4H2O
Products are correct and the equation is correctly balanced. Great job!
Back to the question!
Next question!

52. Quiz Question 5/5
Pick correct rectangle that finishes the reaction below.
Al N2  ??
Al + N2  AlN2
3Al + N2  Al3N2
2Al + N2  2AlN

53. Nope!
Al + N2  AlN2
Remember we do not carry over subscripts. Aluminum has a +3 charge and nitrogen has a -3 charge so a formula of AlN2 is not a neutral compound
Try again!

54. Nope!
3Al + N2  Al3N2
Although this equation is balanced, since aluminum has a +3 charge and nitrogen has a -3 charge, this is not a neutral compound
Try again!

55. Yes! Very good!
2Al + N2  2AlN
A correct neutral compound for the product and a balanced equation. Great!
Back to the question!
Finish!

56. Congratulations! You have finished the chemical reactions tutorial
Go back to the start