Mais les résultats doivent être attendus longtemps et il n'y a généralement pas de temps azithromycine prix L'autre cas, c'est que l'achat d'un ou d'un autre antibiotique dans une pharmacie classique nécessite des dépenses matérielles considérables et pas toutes les personnes ne peuvent acheter des produits pharmaceutiques aussi coûteux.
Properties of Bonds Lab ExerciseChemistry10 points
**NOTE: Only title, heading, goal, research, data, and conclusion need to
The goal of this lab is to determine some properties of ionic and covalent bonds.
In this lab, the melting points of six compounds will be estimated using a Bunsen burner. The electrical conductivity of two of the compounds will also be checked using aconductivity tester.
Research (You may use your notes or a book to answer these):
What happens to the electrons to make an ionic bond?
What happens to the electrons to make a covalent bond?
Which do you predict will have a lower melting point, chemicals with ionic bonds orchemicals with covalent bonds? Why do you think so?
Which do you predict will conduct electricity in solution, chemicals with ionic bonds,chemicals with covalent bonds, both, or neither? Why do you think so?
The student safety contract applies. Sucrose is not considered hazardous. Calcium chlorideis slightly toxic by ingestion and a mild irritant to skin, eyes, and mucous membranes. Sodium chloride is very slightly toxic by ingestion, and its dust may cause minor irritationto mucous membranes upon inhalation. Potassium iodide is irritating to body tissues and apossible sensitizer. Avoid all body tissue contact with potassium iodide. Acetaminophen isslightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, andof inhalation.
Fold the piece of aluminum foil in half.
Attach the iron ring to the ringstand 21 cm above the mouth of the Bunsen burner.
Label six places on the aluminum foil for the six chemicals being used.
Carefully obtain a small sample of each of the six chemicals. (Chemicals may beplaced directly on the aluminum foil. Make sure the chemicals don’t touch each otherand don’t fall off the foil!)
Place the aluminum foil directly on the iron ring.
Heat the chemicals on a LOW flame (no inner cone!) for at least five minutes.
Observe what happens to the chemicals, especially noting their order of melting.
After at least five minutes, turn off the Bunsen burner.
Physically and chemically clean the two beakers and the two stirring rods.
Label one beaker with the name of one of the chemicals that melted quickly.
Obtain a microscoop of the fast-melting chemical in the first labeled beaker.
Add 15 mL of distilled water to the beaker.
Label the other beaker with the name of one of the chemicals that melted slowly (ordidn’t melt in three minutes).
Obtain a microscoop of the slow-melting (or non-melting) chemical in the secondlabeled beaker.
Add 15 mL of distilled water to the beaker.
Use the conductivity tester to see if the solutions conduct electricity. (If theconductivity tester is working, touching its two electrodes together will make the lightbulb light up. If a solution conducts electricity, the light bulb will light up!)
(a) Pour the two solutions into the labeled waste containers.
(b) Place the COOL aluminum foil into the labeled waste container.
(c) Remove the labels on the beakers.
(d) Clean the beakers.
(e) Show the teacher the clean beakers and clean desk for a clean-up signature.
Post-lab questions (in place of a conclusion–answer in your lab book in blue/black ink):
- Please answer in complete sentences! Don’t write the question!1)
List the name of each of the six chemicals used in this lab. Tell which elements makeup each chemical. (Example: Water is made of hydrogen and oxygen.)
Which chemicals contain covalent bonds? Which chemicals contain ionic bonds? How did you decide?
If a chemical melted quickly, does it have a high or low melting point?
Which had a higher melting point, the chemicals with ionic bonds or the chemicalswith covalent bonds?
Which chemical solution(s) conducted electricity, the chemical with an ionic bond, thechemical with a covalent bond, both, or neither?
Based on your data, what are two properties of chemicals with ionic bonds?
Based on your data, what are two properties of chemicals with covalent bonds?
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