Chemical Reactions In A Bag

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Name___________________________________ Block _________________
Group Roles
Mathematician/Data Collector Master: Help the group with any math calculations. Record any
information the group generates to later share with the group. ______________
Materials Master: Collect materials from the teacher, cleans all materials as directed, and return
all materials to the appropriate place. Also assists the procedure master with keeping the group on
task and give encouragement to the group. ______________
Procedure Master: Follow the procedures that the speaking master has read out loud. If you are
unsure of a step, ask the speaking master ______________
Speaking Master: Your primary job is to read the lab out loud and make sure that you do not
continue reading until the procedures have been followed. You will need to keep everyone in the
group on the right step and FOLLOWS ALL DIRECTIONS! You acts as the facilitator. If there is a
question your group needs to ask, it is your job to be the spokes person and ask your teacher
questions. ______________
Chemistry in a bag…
Safety Goggles are required for this lab!
If you remove your safety goggles during this lab, you will be asked to
complete an alternative assignment in place of this lab grade and you will not
be able to participate in the next lab.
Materials
2 cups
Strip of masking tape
1 vile
Calcium Chloride (CaCl2)
Baking Soda (NaOH3)
Phenol Red Solution
1 gallon bag
Graduated Cylinder
Balance
Introducing the Reactants:
In this lab, you will be working with 3 reactants: Calcium Chloride (CaCl2), Baking Soda (NaOH3)
and Phenol Red Solution
Phenol Red Solution:
- It is used to test the pH of swimming pools.
- When a media (solution) becomes acidic, the solution will change from red to yellow.
- In pools, an excess of waste or bacterial contamination will cause the media to become
acidic.
Calcium Chloride
- It is put on roads in winter because it lowers the freezing point of water, preventing ice
from forming.
- - It is commonly used as an electrolyte in sports drinks and other beverages, including
bottled water.
Baking Soda:
- Baking soda reacts with acids in bread to created carbon dioxide.
- It can neutralize acids and is used to treat indigestion, heartburn, and burns.
1
Observations: Before starting the lab, look at the 3 reactants. Each person in
your group will need to make an observation (other than taste) about each of
the reactants. If there are 4 people in your group, each reactant should have 4
observations noted about each of the reactants.
Reactants
Observation
Calcium
Chloride
(CaCl2)
Baking Soda
(NaHCO3)
Phenol Red
Solution
Read over the directions. Do not perform the lab until directed. Once you have
read the directions answer the following questions.
1) What are the differences between an endothermic process and an exothermic process?
2) What do you think will happen when the contents are mixed?
3) What do you think will happen to the mass of the bag when the materials combine?
2
Directions
Getting ready for the lab
1. Mass the empty plastic bag and record the mass below.
2. On the piece of masking tape obtained from your teacher cut the tape into three sections.
3. Label the first section of the tape as “baking soda (NaHCO3)”.
4. Label the second section of the tape as “calcium chloride (CaCl2)”.
5. Label the third section of the tape as “Phenol Red Solution”
Baking Soda Procedures
6. Use the balance to mass the empty cup labeled “baking soda (NaHCO3)”. Record this mass
on the table on page 5.
7. Put 1 of a tablespoon of baking soda (NaHCO3) into a cup.
8. Use the balance to determine the mass of the baking soda and the cup. Record this mass on
the table on page 5.
9. Determine the mass of the baking soda in the cup. (Mass of cup and substance – mass of
the cup)
10. Place the baking soda (NaHCO3) into one corner of your Ziploc bag. (See below image).
Calcium Chloride Procedures
11. Use the balance to mass the empty cup labeled “calcium chloride (CaCl2)”. Record this
mass on the table on page 5.
12. Put 2 Tablespoon of Calcium Chloride (CaCl2) into a cup.
13. Use the balance to determine the mass of the calcium chloride (CaCl2) and the cup.
Record this mass on the table on page 5.
14. Determine the mass of the calcium chloride (CaCl2) in the cup.
(Mass of cup and substance – mass of the cup)
15. Place the Calcium Chloride (CaCl2) into the opposite corner of your Ziploc bag from the
baking soda. (See the below image)
Phenol Red Procedures
16. Use the balance to mass the empty
vile labeled Phenol red solution.
17. Measure 10 ml of Phenol Red
Solution into a graduated cylinder
and pour into the plastic vial.
18. Mass the vial and the 10 ml of
phenol red solution.
19. Put the vial into the bag (Standing
up right), try to carefully squeeze
out as much air as you can without
knocking over the vile.
20. Once you have squeezed out as
much air as possible seal the bag.
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Getting ready for the change
21. Carefully place the bag and it contents on the balance and mass the bag and its contents.
Record this mass on the table on page 5.
22. Tip the vial of Phenol Red in the bag so the baking soda (NaHCO3), calcium chloride (CaCl2)
and Phenol Red Solution can react.
Do not open the Ziploc bag until you have answered the
observation question and the think it over question.
4
Name_____________________________________________ Block________________
Lab Data
✲ Mass of the empty bag ______________________g
✲ Mass of all substances before you mix the substances. ________g
(Mass of the bag + baking soda + calcium chloride + phenol red + vile)
✲ Mass of reactants. ________g
(baking soda + calcium chloride + phenol red + vile)
Baking soda
Calcium Chloride
Phenol Red
Solution
Mass cup / vile
Mass of cup +
substance
Mass substance
(Mass of cup and
substance – mass of the
cup)
Things to remember:
✲ Chemicals that take part in a chemical reaction are called the reactants; the new
substances that form are called the products.
✲ Endothermic reactions – more energy is required to break the bonds holding the reactants
together than is released when the new bond in the products are formed. (Temperature
decreases)
✲ Exothermic reactions- less energy is required to break the bonds holding the reactants
together than s released when the new bonds form in the products. (Temperature
increases)
5
Observation:
When you mixed the reactants, describe what happened inside the bag?
(Temperature, color, mixture, gas produced, sounds, etc)
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
Think it over…
1. In this experiment, was there an example of an exothermic reaction? What evidence in the
lab supports your answer?
2. In this experiment, was there an example of an endothermic reaction? What evidence in
the lab supports your answer?
3. What were the reactants in this experiment?
4. How does the reactants’ mass compare to the product’s mass?
Mass of bag and reactants _______________g
Mass of bag and products ________________g
Compare the mass of the products to the reactants. (How do they compare?)
4. Using your iPad, google the words: “The Conservation of Mass.”
How does question 4 from above relate to the law of mass conservation
(conservation of mass)?
5. What do you think will happen to the mass of the bag if you let the gas in the bag out of the
plastic bag? Why?
6. Carefully open the plastic bag. Is there an odor?
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8. Squeeze out the gas. Re-mass the plastic bag. What happened to the mass after you
squeezed out the gas? Why do you think this happened?
9. If you had different amounts of the reactants do you think your results would change?
.
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