1. Physics and Chemistry 3rd
ESO Albarregas High School
CHEMICAL REACTIONS
Activities
Activity 1:
Which of these processes are physical and which of them are chemical?
a) Fermentation of grape juice in order to get wine.
b) Evaporation of sea water to get salt.
c) Oxidation of iron.
d) Solving coffee in a cup of milk.
e) Burning wood.
f) Gas bubbles escape up from a Coke.
Activity 2:
An oxidated nail weights more than before its oxidation. Does this fact mean that Lavoisier's
law doesn't work? Reason your answer.
Activity 3:
Which of these properties change in chemical processes and which of them don't?
a) The total number of atoms.
b) The total number of molecules.
c) The mass.
d) The volume.
e) Bonds.
Activity 4:
Are these sentence true or false?
a) One mole of a substance has 6.022 10· 23
grams.
b) In chemical processes molecules and atoms change.
c) We can get salt from sea water through a chemical process.
Activity 5:
Fill the gaps. Do the calculations you need.
Carbon dioxyde CO2 is a __________ that we can find in the atmosphere. One mole of this gas
contains 6.022 10· 23
_______________, this involves that 1 mole has ______________ atoms of C and
________________ atoms of H. The ______________ of one mole of a gas only depends on the conditions of
_______________ and temperature. 1 mol of CO2, O2, CH4 or any other gas occupies _________ litres at 1
atm and 273 K.
Activity 6:
How many moles are there in a litre of water? How many molecules? How many atoms?
Activity 7:
Air consists of oxygen (O2) in a 21 percent. How many moles of oxygen are there in 100
litres of air?
Teacher: José Vicente Pacheco Page 1 of 4

2. Physics and Chemistry 3rd
ESO Albarregas High School
Activity 8:
Complete the table. Look for the atomic masses in the periodic table. Remember: NA = 6.022
10· 23
particles/mol; volume of 1 mole of gas (0ºC and 1 atm)= 22,4 litres
Substance Mass (g)
mass of 1
mole (g)
moles molecules atoms
Volume
(litres)
stp conditions
Aluminium
chloride
(AlCl3)
150
Al:
Cl:
Chlorine
(Cl2)
2,5
Ammonia
(NH3)
N:
H:
Sulfur
trioxyde
(SO3)
1024 S:
O:
Activity 9:
Calcium carbonate (CaCO3) is a solid substance at room temperature. If we warm it up
sufficiently, it disappears and two substances appear: calcium oxide, which is solid, and a gas:
carbon dioxyde.
a) Draw the molecules of the three substances that are involved in the reaction.
Calcium carbonate (CaCO3) Calcium oxide (CaO) + carbon doxyde (CO2)
b) Is this a chemical reaction or a physical process?
Activity 10:
The reaction between 21 grams of nitrogen and 9 grams of hydrogen produces 30 grams of
ammonia.
a) Do these data follow Lavoisier's law?
b) What would have happened if we had tried the reaction beteween 21 grams of nitrogen
and 15 grams of hydrogen?
Activity 11:
Calcium hidroxide, Ca(OH)2, and chlorine hydride, HCl, react and produce calcium
chloride, CaCl2, and water.
a) Complete the table writing the formulae and drawing the molecules of products and
reactants.
Teacher: José Vicente Pacheco Page 2 of 4

3. Physics and Chemistry 3rd
ESO Albarregas High School
Reactants Products
Formulae Ca(OH)2 + HCl
Molecules
b) Write and balance the chemical equation of this process, draw the molecules represented
in the balanced equation and check that the number of atoms of each element is the same in both
sides of the arrow
Equation
Molecules Reactants Products
# atoms of Cl
# atoms of Ca
# atoms of H
# atoms of O
Activity 12:
Balance these equations:
a) ___ N2 + ___ O2 ___ NO→ 2
b) ___ K2CO3 + ___ HCl ___ KCl + ___ CO→ 2 + ___ H2O
c) ___ C3H8 + ___ O2 ___ CO→ 2 + ___ H2O
d) ___ Ca(OH)2 + ___ HCl ___ CaCl→ 2 + ___ H2O
e) ___ Al + ___ HCl ___ AlCl→ 3 + ___ H2
f) ___ CuO + ___ HNO3 ___ Cu(NO→ 3)2 + ___ H2O
Activity 13:
Magnesium reacts with oxygen and gives magnesium oxide MgO2.
a) Write and balance the chemical equation of the process.
b) How many moles of magnesium react with one mole of oxygen?
c) How many grams of oxygen react with 48 g of magnesium?
Activity 14:
Copper(II) carbonate breaks down on heating, like this: CuCO3(s) CuO→ (s) + CO2(g)
a) Find the mass of a mole of each substance that take part in the reaction.
b) When 31 g of copper(II) carbonate are used, how many grams of CuO and CO2 are
formed?
Teacher: José Vicente Pacheco Page 3 of 4

4. Physics and Chemistry 3rd
ESO Albarregas High School
Activity 15:
What volume of hydrogen is formes, at stp, when 0.12 g of magnesium reacts with
hydrochloric acid HCl? The chemical equation of this process is: Mg(s) + HCl(g) MgCl→ 2(g) + H2(g)
Activity 16:
What volumen of nitrogen and hydrogen gives 50 dm3
of ammonia gas (stp)? The chemical
equation of this process is: N2(g) + H2(g) NH→ 3(g)
ACTIVITIES FROM YOUR P&C BOOK
Before doing them, I advise you to read carefully the solved samples onm pages 100 and 101.
On page 95: 8
On page 97: 14
On page 101: 17 and 18
On page 104: 26
On page 105: 41
Teacher: José Vicente Pacheco Page 4 of 4