Class presentation for my MYP Intro Chem class.

1. + - + + - + - + + -
Reactions & Formulas
Introductory Chemistry
Canadian Academy
MrT
draft presentation – to be updated

2. The magnesium is combusting.
The magnesium is combining
with oxygen.
There is a physical
change but not a
chemical change.
2

3. Reactions & Formulas
Assessment Statements
• Name simple ionic and covalent compounds from their formula.
• Write formulas for simple ionic and covalent compounds based on
their name.
• Write word equations for reactions.
• Identify reactants and products in reactions.
• Apply state symbols to equations.
• Balance simple formula equations.
• Identify characteristics of reactions:
• ∆ colour
• ∆ temperature (exothermic or endothermic)
• precipitate formation
• gas production
• ∆ pH
• Use conditions for reactions appropriately above the arrow in the
equation (heat, catalyst etc).
• Recognise six types of reaction: synthesis, decomposition, single
replacement, double replacement, combustion and neutralisation.

4. 1 2 13 14 15 16 17 18
+1 +2 -3 -2 -1
non-metals
Periodic table from: http://www.elementsdatabase.com/

5. +1 +2 -3 -2 -1
non-metals
http://commons.wikimedia.org/wiki/Periodic_Table_of_Elements

6. How do we know a reaction has taken place?
• ∆ colour (∆ = ‘change in’)
• ∆ temperature (exothermic or endothermic)
• ∆ pH
• precipitate formation
• gas production
Which of these signs of a chemical reaction have
we come across in our reactions so far?

7. Naming Ions
Remember: metals bonding with
non-metals form ionic bonds.
Some ions are polyatomic. This
means they are made of groups
of atoms which stay together in
reactions – such as carbonates.
What do the elemental anions
have in common in their name?
What do the polyatomic anions
have in common in their name
(except hydroxide)?
What is the difference between
the iron (II) and iron (III) ions?

8. Naming Ionic Compounds
Rules:
• balance the charges
• keep polyatomic ions together
Examples:
HCl hydrogen chloride
NaOH sodium hydroxide
ZnCl2 zinc chloride
Fe2O3 iron oxide
NaOH sodium hydroxide
Pb(NO3)2 lead nitrate

9. Naming Covalent Molecules
Remember: You can only correctly call it a molecule if it is covalently-bonded.
Covalent bonds form between non-metal atoms.
Name the compound this way:
• You don’t need mono- if the first atom is single
• Use the prefixes for all other atoms
Examples:
CO carbon monoxide
CO2 carbon dioxide
N2O3 dinitrogen trioxide
CF4 N2O4 N2H4 H2O

10. Conventions in Writing Reactions
reactants products
conditions for reaction to occur
(e.g. heat, catalysts)
symbol equation
Mg
(s)
+ O2
(g)
heat
MgO
(s)
magnesium + oxygen magnesium oxide
“gives”
word equation
State symbols need to be included:
(s) solid – this included precipitates
(g) gas
(l) liquid
(aq) aqueous solution: solutes dissolved in water
state symbols should be subscripted

11. Wait!
The reactants and products are not balanced
Mg
(s)
+ O2
(g)
heat
MgO
(s)
magnesium + oxygen magnesium oxide

12. Balancing Equations
The Law of Conservation of Mass states that matter is neither created nor destroyed.
There MUST be the same number of atoms on each side of the equation.
Mg
(s)
+ O2 (g) heat
MgO
(s)
magnesium + oxygen magnesium oxide
Reactants Products
Mg 1 1
O 2 1
Simple steps for balancing equations:
1. List & count the elements and groups on each
side of the equation. Don’t split polyatomic ions.
2. Select the compound with the greatest number of
atoms (not counting H and O).
3. Balance the atoms in this compound on both sides
of the equation.
4. Don’t change any compounds.
5. Balance any groups, such as polyatomic ions.
6. Finish up with H and O.

13. Balancing Equations
The Law of Conservation of Mass states that matter is neither created nor destroyed.
There MUST be the same number of atoms on each side of the equation.
Mg
(s)
+ O2 (g) heat
2MgO (s)
magnesium + oxygen magnesium oxide
Reactants Products
Mg 1 1 2
O 2 1 2
Simple steps for balancing equations:
1. List & count the elements and groups on each
side of the equation. Don’t split polyatomic ions.
2. Select the compound with the greatest number of
atoms (not counting H and O).
3. Balance the atoms in this compound on both sides
of the equation.
4. Don’t change any compounds.
5. Balance any groups, such as polyatomic ions.
6. Finish up with H and O.

14. Balancing Equations
The Law of Conservation of Mass states that matter is neither created nor destroyed.
There MUST be the same number of atoms on each side of the equation.
2Mg (s)
+ O2 (g) heat
2MgO (s)
magnesium + oxygen magnesium oxide
Reactants Products
Mg 1 2 1 2
O 2 1 2
Two molecules of Mg are needed to react with one molecule of O2, giving 2 MgO.
Simple steps for balancing equations:
1. List & count the elements and groups on each
side of the equation. Don’t split polyatomic ions.
2. Select the compound with the greatest number of
atoms (not counting H and O).
3. Balance the atoms in this compound on both sides
of the equation.
4. Don’t change any compounds.
5. Balance any groups, such as polyatomic ions.
6. Finish up with H and O.

15. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

16. Synthesis Reactions
These can be simplified as A + B  AB
Where two or more reactants combine to make a single product.
+
CO2 + H2O H2CO3
(g) (l) (aq)
carbon dioxide + water carbonic acid
Reactants Products balanced?
C
O
H

17. Synthesis Reactions
These can be simplified as A + B  AB
Where two or more reactants combine to make a single product.
+
CO2 + H2O H2CO3
(g) (l) (aq)
carbon dioxide + water carbonic acid
Reactants Products balanced?
C 1 1
O 3 3
H 2 2

18. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

19. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2 H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
MnO2 acts as a catalyst in this reaction.
It allows the reaction to take place more quickly but is not used up.
We put it above the arrow. It can be recovered and reused in another reaction.
MnO2

20. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2 H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
MnO2 acts as a catalyst in this reaction.
It allows the reaction to take place more quickly but is not used up.
We put it above the arrow. It can be recovered and reused in another reaction.
MnO2

21. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2 H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
MnO2 acts as a catalyst in this reaction.
It allows the reaction to take place more quickly but is not used up.
We put it above the arrow. It can be recovered and reused in another reaction.
Enzymes are catalysts found in living organisms.
They are proteins with an active site.
MnO2

22. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2 H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
Reactants Products balanced?
O
H

23. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2 H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
Reactants Products balanced?
O 2 3
H 2 2

24. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
MnO2
H2O2
(l)
2H2O + (l)
O2
(g)
hydrogen peroxide water + oxygen
Reactants Products balanced?
O 2 3 4
H 2 2 4

25. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
+
2H2O2 MnO2
2H2O + O2
(l) (l) (g)
hydrogen peroxide water + oxygen
Reactants Products balanced?
O 2 4 3 4
H 2 4 2 4

26. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
Heat
Heat
CuSO4.5H2O CuSO4 + 5H2O (g)
(s) (s)
copper (II) sulphate pentahydrate copper (II) sulphate + water

27. Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into component elements or compounds.
Heat
+
Heat
CuSO4.5H2O CuSO4 + 5H2O (g)
(s) (s)
copper (II) sulphate pentahydrate copper (II) sulphate + water

28. 28

29. Danger: dihydrogen monoxide!
Lethal if inhaled.
Found in disaster zones.
Reduces the effectiveness of brakes.
Found in tumour cells, viruses and deadly bacteria.
Contributes to electrocutions.
Used by terrorists and pirates.
Find out more about this lethal substance: http://www.dhmo.org/facts.html

30. Ionic Covalent
• Don’t use mono-, di- etc in prefixes. • Endings usually –ide.
• Cation, then anion • Don’t need mono- prefix for first
e.g. lithium bromide. atom if it is single (e.g. CH4)
• Don’t break up polyatomic ions. • Name in order of the periodic
table, but H is before O
Remember that in ionic compounds,
the sum of the charges must be zero.
Therefore sodium sulphide is Na2S, not
NaS.
30

31. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

32. Combustion Reactions
This is the combustion (burning) of a hydrocarbon (contains C and H), in oxygen.
Complete combustion results in the products water and carbon dioxide.
CxHx
()
+ O2
(g)
heat
CO2 + H2O
(g) (g)
hydrocarbon + oxygen carbon dioxide + water
e.g
CH4
(g)
+ O2 (g) heat
CO2 + H2O
(g) (g)
methane + oxygen carbon dioxide + water
Reactants Products
C 1 1
O 2 3
H 4 2

33. Combustion Reactions
This is the combustion (burning) of a hydrocarbon (contains C and H), in oxygen.
Complete combustion results in the products water and carbon dioxide.
CxHx
()
+ O2
(g)
heat
CO2 + H2O
(g) (g)
hydrocarbon + oxygen carbon dioxide + water
e.g
CH4 + O2 (g) heat
CO2 +2H2O
(g) (g) (g)
methane + oxygen carbon dioxide + water
Reactants Products
C 1 1
O 2 3 4
H 4 2 4

34. Combustion Reactions
This is the combustion (burning) of a hydrocarbon (contains C and H), in oxygen.
Complete combustion results in the products water and carbon dioxide.
CxHx
()
+ O2
(g)
heat
CO2 + H2O
(g) (g)
hydrocarbon + oxygen carbon dioxide + water
e.g
CH4
(g)
+ 2O2 (g) heat
CO2 +2H2O
(g) (g)
methane + oxygen carbon dioxide + water
Reactants Products
C 1 1
O 2 4 3 4
H 4 2 4

35. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+ O2
(g)
heat
CO2 + H2O
(g) (g)
propane + oxygen carbon dioxide + water
Which product of one of the reactions
we’ve carried out already could be used
to test if the condensation really is water?
Is propane a covalent or ionic compound?
What’s an alternative name for
propane, based on the naming
conventions we have just learned?

36. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+ O2
(g)
heat
CO2 + H2O
(g) (g)
propane + oxygen carbon dioxide + water
Is it balanced?
Reactants Products
C
O
H

37. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+ O2
(g)
heat
CO2 + H2O
(g) (g)
propane + oxygen carbon dioxide + water
Is it balanced?
Reactants Products
C 3 1
O 2 3
H 8 2

38. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+ O2
(g)
heat
3CO2 (g)
+ H2O
(g)
propane + oxygen carbon dioxide + water
Is it balanced?
Reactants Products
C 3 1 3
O 2 3 6
H 8 2

39. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+ O2
(g)
heat
3CO2 +4H2O (g) (g)
propane + oxygen carbon dioxide + water
Is it balanced?
Reactants Products
C 3 1 3
O 2 3 6 10
H 8 2 8

40. Combustion Reactions
A chemical reaction is taking place at the gas tap!
C3H8
(g)
+5O2 (g)
heat
3CO2 +4H2O (g) (g)
propane + oxygen carbon dioxide + water
Is it balanced?
Reactants Products
C 3 1 3
O 2 10 3 6 10
H 8 2 8

41. Combustion Reactions Do NOT try these at home.
Alcohols will also go through combustion reactions.
_CH3OH(l) + _O2(g) heat
___ (g) + ____ (g)
methanol + oxygen carbon dioxide + water
http://www.youtube.com/watch?v=SJCcH0ATMQ4

42. Combustion Reactions Do NOT try these at home.
Alcohols will go through combustion reactions.
_CH3OH(l) + _O2(g) heat
_CO2(g) + _H2O(g)
methanol + oxygen carbon dioxide + water
Balance it!
Reactants Products
C 1 1
O 3 3
H 4 2

43. Combustion Reactions Do NOT try these at home.
Alcohols will go through combustion reactions.
2CH3OH(l) + 3O2(g) heat
2CO2(g) + 4H2O(g)
methanol + oxygen carbon dioxide + water
Balance it!
Reactants Products
C 1 2 1 2
O 3 8 3 8
H 4 8 2 8

44. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

45. Single- & double-replacement and neutralisation reactions
HCl &
NaOH universal
indicator HCl
AgNO3
NaCl
H2O
HCl
CuSO4
NaHCO3
Mg
Fe
Two white solids. Which is
PbNO3 and which is KI?
45

46. Single Replacement Reactions
These can be simplified as AB + C  A + BC
Where an element trades places with another element in a compound.
+ - + + - +
HCl + Mg MgCl2 + H2
(aq) (s) (aq) (g)
hydrogen peroxide magnesium chloride + hydrogen
Reactants Products balanced?
Cl
Mg
H

47. Single Replacement Reactions
These can be simplified as AB + C  A + BC
Where an element trades places with another element in a compound.
+ - + + - +
HCl + Mg MgCl2 + H2
(aq) (s) (aq) (g)
hydrogen peroxide magnesium chloride + hydrogen
Reactants Products balanced?
Cl 1 2
Mg 1 1
H 1 2

48. Single Replacement Reactions
These can be simplified as AB + C  A + BC
Where an element trades places with another element in a compound.
+ - + + - +
2HCl + (aq)
Mg
(s)
MgCl2 + H2
(aq) (g)
hydrogen peroxide magnesium chloride + hydrogen
Reactants Products balanced?
Cl 1 2 2
Mg 1 1
H 1 2 2

49. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

50. Double Replacement Reactions
These can be simplified as AB + CD  AD + CB
Where the anions and cations of two compounds trade places.
+ - + + - + - + + -
KI + Pb(NO3)2 KNO3 + PbI2
(aq) (aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
Reactants Products balanced?
K
I
Pb
NO3
Nitrate is a polyatomic ion and must be kept together

51. Double Replacement Reactions
These can be simplified as AB + CD  AD + CB
Where the anions and cations of two compounds trade places.
+ - + + - + - + + -
KI + Pb(NO3)2 KNO3 + PbI2
(aq) (aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
Reactants Products balanced?
K 1 1
I 1 2
Pb 1 1
NO3 2 1
Nitrate is a polyatomic ion and must be kept together

52. Double Replacement Reactions
These can be simplified as AB + CD  AD + CB
Where the anions and cations of two compounds trade places.
+ - + + - + - + + -
KI
(aq)
+ Pb(NO3)2 2KNO3 + PbI2
(aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
Reactants Products balanced?
K 1 1 2
I 1 2
Pb 1 1
NO3 2 1 2
Nitrate is a polyatomic ion and must be kept together

53. Double Replacement Reactions
These can be simplified as AB + CD  AD + CB
Where the anions and cations of two compounds trade places.
+ - + + - + - + + -
2KI + (aq)
Pb(NO3)2 2KNO3 + PbI2
(aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
Reactants Products balanced?
K 1 2 1 2
I 1 2 2
Pb 1 1
NO3 2 1 2
Nitrate is a polyatomic ion and must be kept together

54. Let’s look at that again…
KI + Pb(NO3)2 KNO3 + PbI2
(aq) (aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
Which ions form?
+
K K
2+
Pb Pb
-
I I
And the polyatomic ion
-
NO3

55. Let’s look at that again…
KI + Pb(NO3)2 KNO3 + PbI2
(aq) (aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
+ - + -
-
K I - K NO3 I
2+ NO3 2+
Pb - Pb -
The 2+ lead cation
needs to be balanced NO3 I
by two single anions.
The total number of atoms on each side are not balanced.
Reactants Products
K 1 1
I 1 2
Pb 1 1
NO3 2 1

56. Let’s look at that again…
2KI + Pb(NO3)2
(aq)
2KNO3 + PbI2
(aq) (aq) (s)
potassium iodide + lead nitrate potassium nitrate + lead iodide
+ - + -
-
K I - K NO3 I
2+ NO3 2+
+ - Pb - + -
Pb -
K I NO3 K NO3 I
Now they are.
Reactants Products
K 1 2 1 2
I 1 2 2
Pb 1 1
NO3 2 1 2

57. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

58. Neutralisation Reactions
These can be simplified as HA + BOH  H20 + BA
Where the acid (HA) is neutralized by the base (BOH), giving water and a salt (AB).
H[A] + [B]OH(aq)
(aq)
[B][A] + H2O
(g) (g)
acid + base salt + water
These brackets don’t get used in equations –
they are just there to show what is happening
e.g
HCl + NaOH(aq)
(aq)
NaCl + H2O
(aq) (g)
hydrochloric acid + sodium hydroxide sodium chloride + water
Reactants Products
Cl
Na
O
H

59. Neutralisation Reactions
These can be simplified as HA + BOH  H20 + AB
Where the acid (HA) is neutralized by the base (BOH), giving water and a salt (BA).
H[A] + [B]OH(aq)
(aq)
[B][A] + H2O
(g) (g)
acid + base salt + water
These brackets don’t get used in equations –
they are just there to show what is happening
e.g
HCl + NaOH(aq)
(aq)
NaCl + H2O
(aq) (g)
hydrochloric acid + sodium hydroxide sodium chloride + water
Reactants Products
Cl 1 1
Na 1 1
O 1 1
H 2 2

60. Types of Reactions
A+B AB AB A+B
replacement
replacement
double
single
AB + C CB + A AB + CD AD + BC
heat
H[A] + [B]OH [B][A] + H2O CxHx + O2 CO2 + H2O

61. Balancing Equation Practice
Now try the activities on this PhET simulation to
help practice balancing equations.
1. Complete the introduction stage.
2. Some of the examples are on the sheet.
3. Try the challenge quizzes.
http://phet.colorado.edu/en/simulation/balan
cing-chemical-equations

62. Classify and balance these…
Cell respiration?
C6H12O6
(s)
+ O2 (g) heat
CO2 + H2O
(g) (g)
glucose + oxygen carbon dioxide + water

63. Housekeeping class
Today we need to make sure everyone is up to date on all work and can
understand balancing and reactions.
1. Check all One World work has been submitted.
2. Check in with incomplete elements task people.
3. Work through last week’s reactions and balance them.
4. Turn these sheets back in to be checked again.
If you have completed everything and are all up to date you can:
• practice balancing and naming using the resources on the GoogleSite
• Find out more about the ‘Mole’ and stoichiometry
MrT’s promise:
• All Chem work will be checked and graded by Thursday
• If you performed poorly in One World you can do another essay or
article in your own time. Due 16 Jan at the very latest.

64. For more resources.
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