Seconde, section euro, Practical course
Test of chemical species in an apple
For each bench (paillasse) :
Practical course n°1 : test of water
- Bunsen burner
- Pliers (pince)
- Beaker (bécher)
- Spatula
- Test tube (×1) + support
- Small plate
- Anhydrous copper sulfate
- Distilled water
- Acetone
Practical course n°2 : test of acidity and starch (amidon)
- Test tube (×4) + support
- pH paper
- solution d’acide chlorhydrique (étiquette possible ? hydrochloric acid) en petit flacon
- solution de chlorure de sodium (étiquette possible ? sodium hydroxide) en petit flacon
- BBT (noté BTB)
- Small Plate
- Agitateur en verre (glass beater)
- Distilled water
- eau iodée (iodine solution)
- poudre d’amidon ?
sinon empois d’amidon (starch solution)
Pain + Pomme de terre
Practical course n°3 : test of sugar
-
Glucose
Test tube (×3) + support
liqueur de Fehling (notée si possible « Fehling’s solution »)
Bunsen burner + matches (allumettes)
distilled water
apple juice or apple or stewed apples (compote) + lemon juice
Seconde, section euro, Practical course
Activity n°1 : Test of chemical species in an apple
You must speak to your partner in ENGLISH during all the course
Lab vocabulary (try to learn it for the next sessions)
Practical course,
labwork
Lab coat
Science lab
Mandatory
Bench or lab bench
Goggles (not google!)
or safety glasses
A drop
Copper
Hydrated
To evaporate
Powder
To conclude
Flame
Travaux pratiques
Pliers (always a “s”)
Pince
Blouse (de labo)
Laboratoire de sciences
Obligatoire
Paillasse
Lunettes de protection
Beaker
Bunsen burner
Pile of xx
Test tube
To pour
Bécher
Bec bunsen
Tas de xx
Tube à essais
Verser
Une goutte
Cuivre
Contains water
S’évaporer
Poudre
Conclure
Flamme
Starch
Spatula
Anhydrous
To heat
Sink
To absorb
To mash, to crush
Amidon
Spatule
Does not contain water
Chauffer
Evier
Absorber
Ecraser
Safety instructions for every chemistry lab :
 wearing a lab coat is mandatory (to protect your clothes and your skin).
 long hair must be attached.
 jackets and schoolbags must be far from the bench at the bottom of the lab.
 wear goggles and gloves only if necessary (for corrosive or toxic chemicals).
Objective of the labwork : to find out which chemical species can be detected in an apple.
I.
Preliminary experiments
1. Experiment n°1
With a spatula, put a little bit of anhydrous copper sulfate in a small plate.
Pour one or two drops of acetone on the anhydrous copper sulfate.
Do the same with distilled water on another part of the plate.
2. Observations
Describe precisely the results of the experiment. You can make a quick drawing of the situation.
What can you say about hydrated copper sulfate ?
Explain how someone can test the presence of water in any object.
3. Experiment n°2
Put a bit of anhydrous copper sulfate in a test tube, then pour a 3 or 4 drops of water on it.
Heat the tube with the Bunsen burner.
4. Observations
Describe precisely the results of the experiment.
Explain the result of the experiment.
II.
Use this test on a piece of an apple
Now you can test the presence of water in a piece of apple.
 Describe your experiment. What do you observe?
 Write a conclusion.
Seconde, section euro, Practical course
Activity n°2 : Test of chemical species in an apple
You must speak to your partner in ENGLISH during all the course
Fill in the chart :
Cork
Bouchon
Above
To shake
Below
To mix
Beater
Agitateur
Glass
Tap water
Eau du robinet
Dropper
Tap
Margin
To match
Dark red, deep red
Compte-goutes
Robinet
Marge
Correspondre
Rouge foncé
To turn to
Starch
Towel
To soak
Light red
Virer au (pour les couleurs)
Amidon
Torchon
Tremper
Rouge clair
The pH is a way to measure the acidity of a solution. A solution is said “acidic” if its pH is below 7, otherwise, it is
“alkaline”.
The bromthymol blue (BTB) is a chemical pH indicator. It is blue when the pH is above 7.6 and it is yellow when the
pH is below 6.0.
 What is the French for “alkaline” ?
I.
Test of acidity : Preliminary experiments
1. Experiment
Work above the sink and pour in the four test tubes :
- In the first one : distilled water
- In the second one : a solution of hydrochloric acid
- In the third one : a solution of sodium hydroxide
- In the fourth one : tap water
 Using a glass beater put a drop of each solution on a very small piece of pH paper.
 In each one of the four test tubes, add a few drops of BTB and shake it a little bit using a cork !
2. Observations
a. Explain how you find out the pH of the solutions using the pH paper.
b. What kind of solutions do you have ? Justify your answers.
c. Write in a few words what you observe in each test tube with the BTB. Can you give the pH of each solution using
the BTB ?
II.
Using this test on an apple
Do a test to find out the acidity of piece of apple.
Describe and explain it, write your observations and conclusion.
III.





Test of starch
Put a little bit of starch powder in a small plate.
Pour one or two drops of iodine solution on it using a dropper.
Do the same test on a piece of potato and a piece of bread.
Propose a test to detect the presence of starch in an apple.
Do the test and write your observations and conclusion.
Seconde, section euro, Practical course
Activity n°3 : Test of chemical species in an apple
You must speak to your partner in ENGLISH during all the course
Fill in the chart :
Amount, quantity
Pliers
To dissolve
Flame
Matches
The reference
Towel
Witness
A report
I.
Un compte rendu
It works
Testing sugar : Preliminary experiment
 Use two test tubes and number them 1 and 2. Put distilled water in each.
 In number two, put a very, very little amount of glucose (it’s sugar). Shake the tube using a cork to dissolve
the glucose.
 Add Fehling's solution in each tube, shake them, and observe the color of the solution.
Safety instructions using the Bunsen burner :
wearing a lab coat is mandatory.
long hair must be attached.
point the tube towards the window or the wall, never towards someone.
if you heat the tube too long, you can cause a projection of solution.
So heat the middle of the solution just a few seconds, then shake the tube, and do it again.
 Using the pliers, you will heat just a little bit (a few seconds) the two test tubes using a
Bunsen burner.
 Describe and explain your experiment, write your observations and conclusion.
Make a quick drawing with colors and a legend showing the test tube before and after heating.
 What is the role of the test tube number 1 ?
II.
Testing sugar in an apple
Propose to the professor an experiment to test the presence of glucose in an apple.
If he agrees, you can perform it.
 Describe and explain your experiment, write your observations and conclusion.
Make a quick drawing with colors and a legend.
 If you have time, you can perform the test on lemon juice and write your conclusion.