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chemistry course exercises
Liceo Scientifico Giordano Bruno – Venezia Mestre
deep purple
chemical reactions and their different speed rates
in accordo con il
Ministero dell’Istruzione, Università, Ricerca
e sulla base delle
Politiche Linguistiche della Commissione Europea
percorso formativo a carattere
tematico-linguistico-didattico-metodologico
scuola secondaria di secondo grado
teacher
Donata Cesare
chemical reactions and their different speed rates
Indice Modulo
Strategies – Before



Prerequisites
Linking to Previous Knowledge and Predicting con questionari basati su stimoli
relativi alle conoscenze pregresse e alle ipotesi riguardanti i contenuti da
affrontare
Italian/English Glossary
Strategies – During



Video con scheda grafica
Keywords riferite al video attraverso esercitazioni mirate
Conceptual Map
Strategies - After

Esercizi:
 Multiple Choice
 Matching
 True or False
 Cloze
 Flow Chart
 Think and Discuss

Summary per abstract e/o esercizi orali o scritti basati su un questionario
e per esercizi quali traduzione e/o dettato

Web References di approfondimento come input interattivi per test orali e
scritti e per esercitazioni basate sul Problem Solving
Answer Sheets
2
chemical reactions and their different speed rates
1
Strategies Before
Prerequisites
reactions
the chemistry
laboratory
the prerequisites are
the prerequisites are
balancing chemical reactions
the mole (unit)
determining the concentration of
a solution
redox reactions
the chemistry laboratory
safety in the lab
glassware
equipment and materials
the speed rate of
chemical reactions
3
chemical reactions and their different speed rates
2
Strategies Before
Linking to Previous Knowledge and Predicting
1. What is a chemical reaction?
2. How do you balance a reaction?
3. What is a solution?
4. How do you measure the concentration of a solution?
5. What is a redox and how do you balance it?
6. What do you mean by a mole and molar mass?
7. What does a body temperature represent?
8. Which is the role of the collisions between particles, in physical and chemical
transformations?
9. What is a catalyst?
10. How can you measure the speed rate of a reaction?
11. Why doesn't the speed rate of the reaction change when you modify the
concentration of the reactants?
12. Why isn't the speed rate of a reaction influenced by an increase in temperature?
4
chemical reactions and their different speed rates
3
Strategies Before
Italian / English Glossary
Accelerare (una reazione chimica)
Acido ossalico
Acido solforico
Aggiungere
Ancoretta Magnetica (d'acciaio ricoperta
di Teflon)
Ascissa (Asse Cartesiano)
Aumentare (Aumento)
Avere l'aspetto di
Bacchetta di vetro
Bagno-maria
Beuta
Bilanciare
Bilancia digitale
Bicchiere
Buretta
Calcolare
Cambiamento
Camice
Catodo
Catalizzatore
Costante ebullioscopica
Chimica
Chimico (agg.)
Cilindro graduato
Cloruro di Manganese
Concentrazione
Cristallizzatore
Cronometro
Dati
Decolorare
Decolorazione
Diluire
Dipendere da
Diminuire, diminuzione
Diossido di Carbonio
Emulsione
Energia di Attivazione
Fusione
Grafico
Guanti
Incolore
Lento
Mascherina
Matraccio
Molare
To Speed up (a chemical reaction)
Oxalic acid
Sulphuric acid
To add
Magnetic Stir Bar(Teflon Coated Stainless
Steel Bar)
X-Axis (Abscissa)
To increase (Increase)
To Look like
Stirring rod
Bains-marie
Conical flask
To balance
Digital scales
Beaker
Burette
To calculate
Change
Lab Apron
Cathode
Catalyst
Ebullioscopic constant
Chemistry
Chemical
Graduated (Measuring) cylinder
Manganese Chloride
Concentration
Crystallizing dish
Stopwatch
Data
To Discolour
Discolouring
To Dilute
To Depend on
To Decrease, Decrease
Carbon Dioxide
Emulsion
Activation energy
Fusion
Graph
Gloves
Colourless
Slow
Face shield
Flat-Bottomed flask
Molar
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chemical reactions and their different speed rates
Molarità
Occhiali Di Protezione
Ordinata (Cartesiana)
Ossidare
Permanganato Di Potassio
Piastra Riscaldante (Con Agitatore
Magnetico)
Pinza
Pila Daniell
Pipetta Graduata
Potenziale Elettrochimico
Polvere
Prendere Il Tempo
Provetta (Provettone)
Rallentare (Una Reazione Chimica)
Rapido
Reagente
Ridurre
Riscaldare (Intiepidire)
Riscaldare A Temperature Elevate
Sassolini (Ghiaia)
Sciogliere
Sicurezza
Sosta Termica
Superficie
Tabella
Temperatura
Termometro
Trasparente
Urto
Versare
Vetreria
Viola
Molarity (Molar Concentration)
Goggles
Y-Axis
To Oxidize
Potassium Permanganate
Hot Plate (With Magnetic Stirrer)
Clamp
Daniell Cell
Graduated Pipette
Electrochemical Potential
Dust
To Time
(Large) Test Tube
To Slow Down(A Chemical Reaction)
Fast
Reactant
To Reduce
To Warm Up
To Heat Up
Gravel
To Dissolve
Safety
Isothermal Period (Stage,Time)
Surface
Chart
Temperature
Thermometer
Transparent, Clear
Collision
To Pour
Glassware
Purple
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chemical reactions and their different speed rates
4
Strategies During
Keywords
1) Circle which of the following words and phrases are associated with the
lab activity on speed rate reactions:
catalyst – fusion – cathode – molarity – activation energy – ebullioscopic constant–
isothermal period – Daniell cell- temperature – surface of the reactants – collisions –
beaker – isotope –pH meter – emulsion – electrochemical potential – magnetic
stirrer
2) Circle which of the following entries are associated with the lab activity
on speed rate reactions:
adding pH-indicator – mechanical stirring – evaporation of the solvent - discolouring
of the solution- to fill up a burette – adding sulphuric acid – pH measuring – adding
ice cubes –diluting the solution – adding the catalyst – measuring the discolouring
time –filtering the suspension – neutralizing an acid solution- mixing the reactants
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chemical reactions and their different speed rates
5
Strategies During
Conceptual Map
Complete the conceptual map using the following words:
the
catalyst
because the
contact among
the reactants
the
discolouring
time
increases
number of collisions
among the particles
by this way
the reaction
is faster
temperature
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chemical reactions and their different speed rates
6
Strategies After
Multiple Choice
1) Which of the following statements gives the right definition of the molar
concentration of a solution?
a. the grams of solute in 100-mL solution
b. the number of solute moles in a 1-litre solution
c. the grams of solute in a 1-kg solution
d. the number of solute moles in a 1-kg solvent
2)
a.
b.
c.
d.
Which of the following reactions is a redox?
H2SO4 + Mg (OH)2  MgSO4+2H2O
FeCl2 + 2KNO3  Fe (NO3)2+2KCl
CaO + H2O  Ca (OH)2
2K + 2H2O  2KOH+H2
3) 30 g of CaCO3 react with 10 mL of HCl 0.1M. In one beaker, CaCO3 looks like
dust, while in another beaker CaCO3 looks like gravel. How does the reaction occur?
a. in the first beaker it takes longer because of the scarce presence of air
b. in the first beaker the reaction will be faster because the contact surface of the
two reactants is much greater
c. in the second beaker the reaction will slow down due to the different
concentration of the reactants
d. the reaction will occur at the same rate speed because the reactants, their
amounts and temperatures are the same
4)
a.
b.
c.
d.
What will happen when the temperature rises in a chemical reaction?
the reaction takes place all the same but the number of collisions decreases
you can observe an increase in the activation energy
an increase in the kinetic energy of the particles involved in the reaction occurs
a different reaction takes place where the activation energy is greater
5) Which of the following statements about the speed rate of a chemical reaction is
false?
a. it is going to be very fast when the activation energy is high
b. it is going to be slow if the reactants come rough and not subdivided
c. it might be helped by certain catalysts
d. it depends on temperature
6)
a.
b.
c.
A catalyst modifies the speed rate of a chemical reaction because
in its presence the products of the reaction are different and are formed faster
its presence always increases the surface on which the molecules can react
it determines an increase of the efficacy and number of the collisions between
molecules
d. it lowers the activation energy
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chemical reactions and their different speed rates
7)
a.
b.
c.
d.
The dilution of a solution containing a reactant determines:
the increase of the reaction speed
the end of the reaction
the slowing down of the reaction
the increase of the number of the collisions between the reactants involved in the
reaction
8) During the reaction between the potassium permanganate and the oxalic acid, a
mechanical mixing of the system has been carried out with the help of an
agitating device. If the mixing was not performed
a. the reaction might stop
b. the reaction would be too fast
c. the reactants would be prevented from meeting
d. temperature and concentration would not be distributed in a homogenized way
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chemical reactions and their different speed rates
7
Strategies After
Matching
Match the definitions (numbers) to the keywords (letters).
1)
A substance that speeds up a chemical reaction without itself undergoing any
permanent chemical change
2)
Clear cylindrical glass tube opened at one end and rounded at the other
3)
A special timing watch with buttons that start, stop and then zero the hands
4)
The number of moles of solute dissolved in 1 litre of solution
5)
A container holding hot water into which another container is placed for slow
warming up
6)
Teflon coated stainless steel bar used to mix 2 substances
7)
Close-fitted eye-glasses with side shields
8)
Sterile glass tubes used to mix 2 substances together
9)
Digital instrument for weighing
10) A lipped cylindrical glass container for holding liquids
11) Protective garment worn over the front of one's clothes
12) A substance that takes part in and undergoes change during a reaction
a)
magnetic stir bar
b)
goggles
c)
lab apron
d)
beaker
e)
test tube
f)
scales
g)
bains-marie
h)
catalyst
i)
stopwatch
j)
stirring rod
k)
molarity
l)
reactant
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chemical reactions and their different speed rates
8
Strategies After
True or False
State if the following sentences are true (T) or false (F).
1) A catalyst is a particular reactant which speeds up the reaction
2) The decrease in temperature slows down the molecules
3) The reaction speed is measured in metres per second
4) The discolouring of the solution of potassium permanganate marks
the end of the reaction you watched in the video
5) The catalyst used in the same reaction is a specific enzyme
6) Activation energy decreases in the presence of the catalyst
T
T
F
F
T
T
F
F
T
T
T
F
F
F
T
F
T
F
T
F
7) The molarity of a solution is the number of moles in a liter of
solute
8) The zero of the absolute temperature corresponds to -273.15 °C
9) A graduated cylinder allows to measure the mass of the solution
10) The collisions between particles are favoured by the increase in
the concentration of the reactants.
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chemical reactions and their different speed rates
9
Strategies After
Cloze
Complete the text.
In a chemical reaction , the transformation of reactants into……………...[1] usually
occurs through the breaking of the chemical……….……..[2] among the atoms of the
reactants; this requires an initial intake of ………………..[3] energy of the reaction.
Besides it is necessary for the molecules to collide with each other, which is favoured
by the high …………….…..[4] of the reactants, therefore, when the solution containing
the reactant is diluted, the reaction time ………………..[5] increases. Also the increase
in temperature speeds up the reaction; the molecules involved in the reaction,
acquiring energy increase their movement and the ………..………..[6] become more
numerous and effective. The presence of the ………………...[7] favours the contact of
the reactants and the breaking of the chemical links.
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chemical reactions and their different speed rates
10
Strategies After
Flow Chart
Complete the flow chart representing the reaction shown in the video.
You can use the terms listed below:
add the oxalic acid – mix – add the sulphuric acid – measure the discolouring
time – take the potassium permanganate
start
end
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chemical reactions and their different speed rates
11
Strategies After
Think and Discuss
The following activity can be performed in a written or oral form. The teacher will
choose the modality, depending on the ability (writing or speaking) that needs to be
developed.
The contexts in which the task will be presented to the students are:
A) the student is writing an article about chemical reactions and their different speed
rates.
B)the student is preparing for an interview on a local TV about chemical reactions
and their different speed rates.
The student should:
1) Choose one of the following topics:
 The importance of catalysts in chemical industry
 The role of enzymes as biological catalysts
2) Prepare the article or the debate, outlining the main points of the argument, on
the basis of what has been studied.
3) If the written activity is the modality chosen by the teacher, the student should
provide a written article, indicating the target of readers to whom the article is
addressed and the type of magazine / newspaper / school magazine where the
article would be published.
4) If the oral activity is the modality chosen by the teacher, the student should
present his point of view on the topics to the whole class and a debate could start at
the end of his presentation.
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chemical reactions and their different speed rates
12
Strategies After
Summary
Chemical reactions occur at different speed rates: some are very fast, some are very
slow.
The speed rate depends on the nature of the reactants but there are other factors,
such as the concentration of the reactants, the temperature, the presence of a
catalyst and the surface area of reactants.
By increasing the concentration of reactants, the total number of particles increases
and this favours the collision between the reactants; the increase on temperature
increases the kinetic energy of the particles. The collisions become more numerous
and effective.
A catalyst is a substance that increases the speed of a reaction, without itself
undergoing any permanent chemical change, it can be recovered at the end of a
reaction and used again. A catalyst reduces the activation energy of a reaction, then
the reaction is faster. An enzyme is a large molecule (usually a protein) that
catalyzes biochemical reactions.
When solids are involved in chemical reactions only surface particles are exposed. In
this way they are the only ones that can collide with the particles of other reactants.
When you break up a lump into smaller pieces, the number of particles does not
change but the number of surface particles increases, there is a greater surface area,
so more collisions can occur hence the reaction is faster.
In the course of the lab activity, students analyze the effects of the following factors
on the speed rate of a reaction: the concentration of the reactants, the presence of a
catalyst and the temperature.
The goal of the experiment is to verify how a redox between potassium
permanganate (KMnO4) mixed with sulphuric acid, on oxalic acid (C2H2O4) is
influenced by the following factors: gradual decrease in the concentration of the
reactants, presence of a catalyst, gradual increase in the temperature.
This reaction occurs:
2KMnO4 + 5C2H2O4 + 3H2SO4  2MnSO4 + K2SO4 +10CO2 + 8H2O
The reaction occurs and you can see the gradual discolouring process in the initial
purple solution of potassium permanganate through the following stages: purple,
red, orange, yellow, colourless. When the solution is colourless, the reaction is over.
The discolouring time is measured with a stopwatch.
Adding 20mL, then 40mL and then 60mL of water you can see the effect of
different concentrations of the reactants.
In the presence of a catalyst the discolouring time of the reaction decreases,
therefore, the reaction is faster.
Using solutions of potassium permanganate with the same concentration, but in a
beaker with water at different temperatures, you can notice that the higher the
temperature, the faster the discolouring.
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chemical reactions and their different speed rates
1) Answer the following questions. The questions could be answered in a
written or oral form, according to the teacher’s objectives.
a) Which are the factors that influence the speed of a chemical reaction?
b) What is a chemical reaction?
c) Which are the functions of catalyst?
d) How do you dilute a solution?
e) Which is the function of a magnetic stirrer ?
f) What is a beaker?
g) What is the colour of the permanganate solution?
2) Write a short abstract of the summary (max 150 words) highlighting the
main points of the video.
17
chemical reactions and their different speed rates
Web References
Velocity of chemical reactions
http://www.chem.msu.su/eng/teaching/Kinetics-online/welcome.html
General Chemistry Glossary
http://antoine.frostburg.edu/chem/senese/101/glossary.shtml
http://www.proz.com/glossary-translations/english-to-italian-translations/19/40
Chemistry Fundamentals
http://www.shodor.org/UNChem/
International Union of Pure and Applied Chemistry
http://www.iupac.org/
Interesting computer simulations
vimeo.com/7219809 (Protein expression Study N. 2)
vimeo.com/12363247 (Protein expression Study N. 3)
http://www.scivis.ifc.cnr.it/
Webcast lectures, teachers' resources, archives
http://www.hhmi.org
Repository for science education resources
http://www.xplora.org
Search engine for videos on scientific subjects
http://www.sciencehack.com
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chemical reactions and their different speed rates
13
Activities Based on Problem Solving
The following activities can be performed at school, if a computer room is
available, or at home. Students are invited to use the web references listed
above.
1) Individual activity.
Choose one of the following topics related to enzymes, use the web
references listed above, prepare a Power Point presentation and present it
to your classmates.
a. Analyze the importance of the enzymes in biological reactions
b. Describe the way an enzyme performs its action of catalysis
c. Explain how enzyme-substrate specificity is done
2) Small group activity.
Choose one of the following topics related to applied chemistry of the
factors that influence the speed rate of a reaction, use the web references
listed above, prepare a Power Point presentation and present it to your
classmates in turns.
Topics:
a. The industrial production of ammonia
b. The role of the catalyst in the gas released by a car engine
3) Class project.
Design poster and a brochure showing the required behaviour in the
chemistry laboratory.
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chemical reactions and their different speed rates
Answer Sheets
Keywords:
1. catalyst, molarity, activation energy, temperature, surface of the reactants,
collisions, beaker, magnetic stirrer
2. mechanical stirring, adding sulphuric acid, discolouring of the solution, diluting of
the solution, mixing the reactants, adding the catalyst, measuring the discolouring
time
Conceptual Map:
The reaction speed rate
is influenced by
number of collisions
among the particles
activation energy
which increases
with
concentration
of reactatnts
Therefore,
diluting
the reactants
the
discolouring
time
increases
which decreases
with
temperature
surface area
of the reactants
because the
kinetic energy
of the
reactants
because the
contact among
the reactants
is more
frequent
increases
20
the
catalyst
by this way
the reaction
is faster
chemical reactions and their different speed rates
Multiple Choice:
1b, 2d, 3b, 4c, 5a, 6d, 7c, 8d
Matching:
1h, 2e, 3i, 4k, 5g, 6a, 7b, 8j, 9f, 10d. 11c, 12l
True or False:
1 F, 2 T, 3 F, 4 T, 5 F, 6 T, 7 F, 8 T, 9 F, 10 T
Cloze:
[1] products, [2] links, [3] activation, [4] concentration, [5] increases, [6]
collisions, [7] catalyst
Flow Chart:
start
take the potassium permanganate
add the sulphuric acid
add the oxalic acid
mix
measure the discolouring time
end
Materiale sviluppato da eniscuola nell’ambito del protocollo d’intesa con il MIUR
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