deep purple -...

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


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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


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1

Strategies Before Prerequisites

reactions

the chemistry laboratory

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

the prerequisites are the prerequisites are


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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?


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3

Strategies Before Italian / English Glossary

Accelerare (una reazione chimica) To Speed up (a chemical reaction) Acido ossalico Oxalic acid Acido solforico Sulphuric acid Aggiungere To add Ancoretta Magnetica (d'acciaio ricoperta di Teflon)

Magnetic Stir Bar(Teflon Coated Stainless Steel Bar)

Ascissa (Asse Cartesiano) X-Axis (Abscissa) Aumentare (Aumento) To increase (Increase) Avere l'aspetto di To Look like Bacchetta di vetro Stirring rod Bagno-maria Bains-marie Beuta Conical flask Bilanciare To balance Bilancia digitale Digital scales Bicchiere Beaker Buretta Burette Calcolare To calculate Cambiamento Change Camice Lab Apron Catodo Cathode Catalizzatore Catalyst Costante ebullioscopica Ebullioscopic constant Chimica Chemistry Chimico (agg.) Chemical Cilindro graduato Graduated (Measuring) cylinder Cloruro di Manganese Manganese Chloride Concentrazione Concentration Cristallizzatore Crystallizing dish Cronometro Stopwatch Dati Data Decolorare To Discolour Decolorazione Discolouring Diluire To Dilute Dipendere da To Depend on Diminuire, diminuzione To Decrease, Decrease Diossido di Carbonio Carbon Dioxide Emulsione Emulsion Energia di Attivazione Activation energy Fusione Fusion Grafico Graph Guanti Gloves Incolore Colourless Lento Slow Mascherina Face shield Matraccio Flat-Bottomed flask Molare Molar


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Molarità Molarity (Molar Concentration) Occhiali Di Protezione Goggles Ordinata (Cartesiana) Y-Axis Ossidare To Oxidize Permanganato Di Potassio Potassium Permanganate Piastra Riscaldante (Con Agitatore Magnetico)

Hot Plate (With Magnetic Stirrer)

Pinza Clamp Pila Daniell Daniell Cell Pipetta Graduata Graduated Pipette Potenziale Elettrochimico Electrochemical Potential Polvere Dust Prendere Il Tempo To Time Provetta (Provettone) (Large) Test Tube Rallentare (Una Reazione Chimica) To Slow Down(A Chemical Reaction) Rapido Fast Reagente Reactant Ridurre To Reduce Riscaldare (Intiepidire) To Warm Up Riscaldare A Temperature Elevate To Heat Up Sassolini (Ghiaia) Gravel Sciogliere To Dissolve Sicurezza Safety Sosta Termica Isothermal Period (Stage,Time) Superficie Surface Tabella Chart Temperatura Temperature Termometro Thermometer Trasparente Transparent, Clear Urto Collision Versare To Pour Vetreria Glassware Viola Purple


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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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Strategies During Conceptual Map

Complete the conceptual map using the following words:

the catalyst

by this way the reaction is faster

number of collisions among the particles

temperature

the discolouring time

increases

because the contact among the reactants


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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) Which of the following reactions is a redox? a. H2SO4 + Mg (OH)2 � MgSO4+2H2O b. FeCl2 + 2KNO3 � Fe (NO3)2+2KCl c. CaO + H2O � Ca (OH)2 d. 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) What will happen when the temperature rises in a chemical reaction? a. the reaction takes place all the same but the number of collisions decreases b. you can observe an increase in the activation energy c. an increase in the kinetic energy of the particles involved in the reaction occurs d. 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 catalyst modifies the speed rate of a chemical reaction because a. in its presence the products of the reaction are different and are formed faster b. its presence always increases the surface on which the molecules can react c. it determines an increase of the efficacy and number of the collisions between molecules

d. it lowers the activation energy


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7) The dilution of a solution containing a reactant determines: a. the increase of the reaction speed b. the end of the reaction c. the slowing down of the reaction d. 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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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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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

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.

� T � F � T � F � T � F � T � F

� T � F � T � F � T � F � T � F � T � F � T � F


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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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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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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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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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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.


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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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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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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

temperature

is more frequent

because the contact among the reactants

surface area of the reactants

because the kinetic energy

of the reactants

which decreases with

by this way the reaction is faster

the catalyst

the discolouring time

increases

increases


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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:

Materiale sviluppato da eniscuola nell’ambito del protocollo d’intesa con il MIUR

start

take the potassium permanganate

add the sulphuric acid

add the oxalic acid

mix

measure the discolouring time

end

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