let’s get started!!. goals in this tutorial, you will learn… how to recognize 3 of the 5 types...
TRANSCRIPT
CHEMICAL REACTIONS TUTORIAL
Let’s get started!!
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
What are the 5 types of reactions?
Synthesis
Decomposition
CombustionSingle replacement
Double replacement
Which 3 will be we learning about??
Synthesis
Decomposition
Combustion
SYNTHESIS
Synthesis
Two or more reactants combine to form… ONE
PRODUCT!!
A + B
AB
Synthesis Continued
Mg + O2 MgO
Two reactants form one product
BUT WAIT!!Don’t forget about everything you have already
learned! Is your equation balanced??
2 2
Before we keep going… lets learn a few things about predicting products
Predicting products
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
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
Why O2??
What are the other diatomic elements? (hint: remember the heavenly 7!
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!
Go back
H2 I2
Br2 O
2
N2 Cl
2
F2
Now to predict the products…
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??
Mg + O2
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?
Mg 2+
What’s the charge of O?
O 2-
So what’s the compound?
Mg2
+
O2-Pick…
MgO2
Mg2O2
MgO
Nope!
+2 + 2(-2)
DOES NOT EQUAL ZERO
MgO2
Try again!
Nope!
2(+2) + 2(-2) = 0
But remember ionic compounds need to be in the simplest form
Mg2O2
Try again!
Yes! Very good!
MgO is a neutral, correct ionic compound so our formula is
Mg + O2 MgOFinally, balance the equation to satisfy the law of conservation of mass…
2Mg + O2 2MgO
So remember…
When predicting products: Make correct ionic compounds THEN balance
Let’s move on to the rest of the reaction types…
Decomposition
Decomposition
forms two or more products
ONE REACTANT…
A + BAB
Decomposition Continued
The electrolysis of water is when water decomposes into hydrogen and oxygen gas as shown below:
2H2O 2H2 + O2
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?
No!
Remember, H and O are both diatomic elements.
H2O H2 + O2
But wait….something is still missing….
Balance!
Don’t forget to balance your equation after you make your products! Your final answer should look like this:
2H2O 2H2 + O2
You try one…
What is the correct reaction for the decomposition of sodium chloride, NaCl?
NaCl Na + Cl
2NaCl 2Na + Cl2
2NaCl Na2 + Cl2
Nope!
Don’t forget that chlorine is a diatomic element, so it must be Cl2
NaCl Na + Cl
Try again!
Nope!
Although this reaction is correctly balanced, sodium is NOT a diatomic element
2NaCl Na2 + Cl2
Try again!
Yes! Very good!
This is a correct reaction for the decomposition of sodium chloride.
2NaCl 2Na + Cl2
Ready for the last type of reaction?
Combustion
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
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??
CH4
C6H10
C20H4
2
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…
Combustion Cont.
Be aware… this reaction was pretty easy to balance, some of the combustion reactions get pretty complicated! Like this one…
CH4 + O2 CO2 + 2H2O
4C3H9 + 21O2 12CO2 + 18H2O
Ready for your quiz??
Yes!
Not quite, review the types of reactions
with me…
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!
Quiz Question 1/5
Which of the following is a decomposition reaction?
2Fe + O2 2FeO
Na + AgCl Ag + NaCl
Na2S 2Na + S
Nope!
This is two reactants forming ONE product which is an example of a synthesis reaction
2Fe + O2 2FeO
Try again!
Nope!
This reaction does not just form one product. This reaction is an example of a single replacement reaction which we will learn about later.
Na + AgCl Ag + NaCl
Try again!
Yes! Very good!
This reaction is ONE reactant breaking down into two or more products, which is an example of a decomposition reaction.
Na2S 2Na + S
Next question
!
Back to the
question!
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.
Nope!
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!
A combustion reaction is the only reaction always has at
least two reactants and two products. One of the reactants is always oxygen
gas.
Nope!
Although combustion reactions are typically explosive, it is not because they react with nitrogen.
Try again!
A combustion reaction always
has a hydrocarbon reacting with
nitrogen, which is a very explosive
reaction.
Yes! Very good!
This is how we identify a combustion reaction
Next question
!
A combustion reaction always
has a hydrocarbon reacting with
oxygen to produce carbon dioxide
and water.
Back to the
question!
Quiz Question 3/5
Pick correct bubble that finishes the reaction below.
K + Cl2 ??
2K + Cl2 2KCl
K + Cl2 KCl2
K + Cl2 KCl
Nope!
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!
K + Cl2 KCl2
Almost! But not quite…
Although this product is correct, the equation is not balanced!
Try again
!
K + Cl2 KCl
Yes! Very good!
The products are correct and the reaction is balanced! Great job!
Next questio
n!
2K + Cl2 2KCl
Back to the
question!
Quiz Question 4/5
Pick correct rectangle that finishes the reaction below.
C2H8 + O2 ??
C2H8 + O2 CO2 + H2O
C2H8 + O2 C2H8O2
C2H8 + 4O2 2CO2 + 4H2O
Almost, but not quite…
Great job predicting the products, but…. don’t forget to balance!!
Try again!
C2H8 + O2 CO2 + H2O
Nope!
Remember that combustion reactions always have carbon dioxide and water as products
Try again!
C2H8 + O2 C2H8O2
Yes! Very good!
Products are correct and the equation is correctly balanced. Great job!
Back to the
question!
Next question!
C2H8 + 4O2 2CO2 + 4H2O
Quiz Question 5/5
Pick correct rectangle that finishes the reaction below.
Al + N2 ??Al + N2 AlN2
3Al + N2 Al3N2
2Al + N2 2AlN
Nope!
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!
Al + N2 AlN2
Nope!
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!
3Al + N2 Al3N2
Yes! Very good!
A correct neutral compound for the product and a balanced equation. Great!
Finish!
Back to the question!
2Al + N2 2AlN
You have finished the chemical reactions tutorial
Congratulations!
Go back to the start