I use this lab sequence over a couple of lessons to get to grips with some basics of different types of reactions, balancing, writing formulas and problem-solving.

1. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Reactions and Formulas
In this unit, we will learn about the characteristics of different types of reactions, as well as how to
name compounds and balance chemical formulas.
Assessment Statements
 Write word and formula equations using accepted conventions.
 Apply appropriate state symbols to reactants and products in reactions
 Annotate the conditions required for a reaction (such as heat or presence of a catalyst) above and/or below the
arrow in a reaction.
 Identify and name ionic and covalent compounds
 Outline the characteristics of major types of reactions, with examples.
 Balance simple formula equations and show your working.
Quiz Quizzes to complete:
 3.1 Types of Reactions (http://www.quia.com/quiz/3644575.html)
 3.2 Naming ionic and covalent compounds (http://www.quia.com/quiz/3644603.html)
Self-assessment: Attitudes in Science
Level Level descriptor
0 The student does not reach a standard described by any of the descriptors below.
1–2 The student requires some guidance to work safely and some assistance when using material and equipment.
The student requires some guidance to work responsibly with regards to the living and non-living environment.
When working as part of a group, the student needs frequent reminders to cooperate with others.
3–4 The student requires little guidance to work safely and little assistance when using material and equipment.
The student works responsibly with regards to the living and non-living environment.
When working as part of a group the student cooperates with others on most occasions.
5–6 The student requires no guidance to work safely and uses material and equipment competently.
The student works responsibly with regards to the living and non-living environment.
When working as part of a group, the student cooperates with others.

2. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Synthesis Reactions
In these reactions, one or more reactants are combined to form one product.
These can be simplified as A + B  AB
Let’s use the example of magnesium reacting with oxygen
to learn about how to write equations.
Ignite a piece of magnesium in the Bunsen roaring flame, using tongs.
Safety: goggles, tongs. DO NOT LOOK DIRECTLY AT THE REACTION. Follow the demonstration.
This is not burning or combustion.
State symbols are shown subscripted in brackets next to each element or compound. This is important
information which tells us about the phase or state of the chemical.
(s) represents solids. This includes precipitates which form, such as in suspensions.
(g) represents gases. These could be observed as bubbles or smelled as fumes.
(l) represents liquids. These are substances in their liquid state – not solutions.
(aq) represents aqueous solutions. This means a solute dissolved in water.
Balancing Formula Equations
Remember the Law of Conservation of Mass? Atoms can neither be created nor destroyed. This means that
there must be the same number of atoms of each element on the products side as on the reactants side.
Use the method outlined below and show your working. Adjust the symbol equation above.
1. List and count the elements and groups on each side of the reaction. Don’t split polyatomic ionc.
2. Identify the compound with the greatest number of atoms.
3. Balance the atoms in this compound on both sides of the equation, without changing the compound!
4. Balance any groups (such as polyatomic ions).
5. Finish up with H and O.
Mg + O2 -----------> MgO
Reactants Products
Mg
O

3. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Another synthesis reaction
Blow gently into a flask of water while measuring the pH.
Safety:Blow gently, don’t drink. Use goggles.
“reversible reaction”
CO2 (g)+ H2O(l) H2CO3 (aq)
carbon dioxide (g) + water (l) carbonic acid(aq)
Observations: What happens to the pH of the water as you blow into the flask?
Is the formula equation balanced? Use the method we practiced.
CO2+ H2 O -----------> H2CO3
Reactants Products
C
O
H
Why is CO2 called carbon dioxide? Naming ionic and covalent compounds.
1. Identify if the compound is ionic or covalent.
2. Name it, using the rules below.
Naming ionic compounds Naming covalent compounds
Pick the ion names from the list. Put the cation before the anions. The ending of the last element in the
You do not need to use ‘mono-‘ ‘di-‘ etc. compound usually becomes –ide.
They are in the same horizontal order as the
periodic table, except H comes before O.
Prefixes are given based on the number of
atoms:mono: 1. di: 2. tri: 3. tetra: 4.
penta: 5. hexa: 6.
Mono- is not often used with the first element
in the compound if it is a single atom.
Name these examples:
1. CH4 - ---------------------------------
2. CaS ---------------------------------
3. N2H4 ---------------------------------
4. MgI2 ---------------------------------
5. FeO iron (II) oxide
6. Fe2O3---------------------------------
Complete Quia Quiz 3.1: Naming compounds

4. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Decomposition Reactions
These can be simplified as AB  A + B
Where a single reactant breaks down into
component elements or compounds.
Decomposition of hydrogen peroxide using a catalyst
Add a small amount of the catalyst MnO2 to about 10ml H2O2
Use a flame test to determine which gas is produced.
Safety: goggles. Take care with the flame test.
H2O2 (aq) ----------->
hydrogen peroxide(aq) ----------------->
Observations, changes and evidence that a chemical reaction has taken place.
MnO2 is not included as a reactant or product. Where should it be written in the reaction? Add it.
Describe the role of a catalyst in chemical reactions.
Balance the formula equation.
Heating copper(II) sulphatepentahydrate
Heat the blue crystals in a boiling tube, over a bunsen flame
Observe the changes in the test tube carefully.
Safety: goggles, tongs. DO NOT POINT AT ANYONE!
CuSO4.5H2O -----------> CuSO4+ H2O
copper (II) sulphatepentahydrate ----------------->
Observations, changes and evidence that a chemical reaction has taken place.
Think: why is the reactant called copper (II)sulphate (what’s the (II) for?)
Add the conditions for the reaction above the arrow.
What happens when you add water to the tube again?

5. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Combustion Reactions
Hydrocarbons contain – wait for it… hydrogen and carbon. They react with oxygen in the presence of
heat through the process of combustion. When combustion is complete (there is no hydrocarbon left),
all that remains is carbon dioxide and water.
We combust a hydrocarbon in our science lab all the time – propane!
Safety: flame safety.
C3 H 8 + O2 ----------->
propane + oxygen ----------------->
Observations, changes and evidence that a chemical reaction has taken place.
Which of the products we’ve made so far could be used to test if the condensation in this reaction really
is water?
Using the naming conventions we’ve learned, suggest an alternative name for propane.
Balance it!
Reactants Products Don’t forget to complete the
C word and formula equations
and add state symbols.
H
O
Alcohols can also be combusted. Observe the demonstration with methanol.
CH3OH+ O2 ----------->
methanol + oxygen ----------------->
Balance it!
Reactants Products Don’t forget to complete the
word and formula equations
and add state symbols.

6. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Single Replacement Reactions
These can be simplified as AB + C  A + BC
An element or ion has changed places with another element or ion.
Reaction 1: Copper sulphate solution and iron (II)
Get this one going early. It takes a while.
Mix iron powder and copper sulphate solution in a test tube and wait.
CuSO4(aq)+ Fe(s) -----------> FeSO4+ Cu
coppersulphate + iron ----------------->
Observations, changes and evidence that a chemical reaction has taken place.
Reactants Products Sulphate is a polyatomic ion,
so it must remain together.
Cu
SO4 Check the word equation and
Fe state symbols.
Reaction 2: Magnesium and hydrochloric acid.
Add a piece of magnesium to about 10ml HCl.
Safety: goggles. Take care with the flame test.
Mg + HCl -----------> H2 + MgCl2
magnesium + hydrochloric acid ----------------->
Explain why the formula for hydrogen chloride HCl, but magnesium chloride is MgCl2. (Think: ions!)
Reactants Products
Check the word equation and
Mg state symbols.
H
Cl

7. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Double Replacement Reactions
These can be simplified as AB + CD  AD + CB
Where the anions and cations of two compounds trade places.
Reaction 1: Sodium chloride solution and silver nitrate solution
Pour the NaCl solution into the AgNO3 solution
Safety: goggles.
NaCl+ AgNO3 ----------->
----------------->
The white precipitate formed is a suspension. What does this mean?
Reactants Products
Again, polyatomic ions must
remain together.
Complete the word and
symbol equations, with state
symbols.
Reaction 2: Potassium iodide and lead nitrate
Set up a petri dish with a thin layer of water
Very carefully add the two solids to opposite ends of the dish
Safety: goggles. Give the finished reaction to MrT to dispose of carefully.
KI+ Pb(NO3)2 -----------> KNO3+ PbI2
potassium iodide + lead nitrate ----------------->
Observe the diffusion and reaction. Deduce which of the solids was which. Explain your reasoning.
Reactants Products
Again, polyatomic ions must
remain together.
Complete the word and
symbol equations, with state
symbols.

8. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
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 (AB).
Reaction 1: hydrochloric acid (with universal indicator) and sodium hydroxide
Add the NaOH solution, dropwise, to the HCl solution.
Safety: goggles!
HCl+ NaOH -----------> H2O+ NaCl
hydrochloric acid + sodium hydroxide ----------------->
Observations, changes and evidence that a chemical reaction has taken place.
How could you prove experimentally that the salt produced is sodium chloride?
Reactants Products
H Complete the word and
symbol equations, with state
Cl symbols.
Na
O
Reaction 2: A special case: hydrochloric acid and sodium hydrogencarbonate
Add the NaHCO3 to the flask of HCl
Safety: goggles!
HCl+ NaHCO3 -----------> H2 O + NaCl + CO2
hydrochloric acid + sodium hydroxide ----------------->
Note: baking soda (sodium hydrogencarbonate) is amphoteric. It acts as a base or as an acid. Cool.
Carbon dioxide is not normally produced in simple acid-base reactions.
Reactants Products
H Complete the word and
symbol equations, with state
Cl symbols.
Na
O

9. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Identifying and balancing reactions practice
In each case, identify the type of reaction (circle it) and explain your choice.
Complete the word and symbol equations. Balance the symbol equation and show your working.
Reaction 1: Inside our cells!
C6H12O6+ O2 -----------> CO2+ H2 O
glucose + oxygen ----------------->
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:
Reaction 2: electrolysis of water
H2 O -----------> H2 + O2
water ----------------->
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:
Reaction 3: making ethane from acetylene
C2 H2 + H2 -----------> C2 H6
acetylene + hydrogen -----------------> ethane
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:

10. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Reaction 4: using the ethane
C2 H 6 + O2 -----------> CO2 + H2 O
+ ----------------->
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:
Reaction 5: reaction of iron (II) sulphide with hydrochloric acid
FeS+ HCl -----------> FeCl2 + H2S
+ ----------------->
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:
Explain why iron bonds with two chlorides and two hydrogens are needed to bond with one sulphur.
Reaction 6: sulphuric acid and potassium hydroxide
H2SO4+ KOH -----------> K2SO4+ H2O
Potassium sulphate +
+ ----------------->
(a salt)
Type:synthesis decomposition combustion single-replacement double-replacement neutralization
Reason:
Balance it:

11. Grade 9 Introduction to Chemistry Student Name: _________________________
Reactions & Formulas Date: _______
Six Main Types of Chemical Reaction
Indicators of a chemical change:
Precipitate Formation (a new solid is formed, or the solution becomes very cloudy as tiny new solid
particles are suspended in the solution)
Temperature Change
 Exothermic – gets hotter. Energy is released as bonds between atoms are broken.
 Endothermic– gets colder. Energy is taken in to make new bonds.
Colour Change (no colour = “colourless”)
Gas Production (bubbles – think about how you would test the gas)
Change in odor (smell) – be sure to check this safely
The Law of Conservation of Mass“Matter can neither be created nor destroyed”
This means that the same number of atoms of each element must exist on the reactants side and on
the products side. If not, it needs to be balanced!