HW #8 for 3/31

HW #8 pg. 350 #2, 4-6

Cold Pack Design Lab

Designing a Cold Pack Group Investigation

Background: An instant cold pack is a first aid device used to treat injuries.  The pack that we used in class contains two plastic bags: one contains an ionic compound (salt) and the smaller bag contains water.  When the water bag is broken, the water reacts with the salt to create an endothermic reaction.

Your task: Your group will investigate different salts for potential use in a cold pack.  Using data from your own experimentation along with the cost data below, your group must decide which salt is the best choice for your product.  You must keep in mind that you are deciding:

1)     Which salt will be used

2)     The quantity of salt and water to be used

3)     What your laboratory set up and procedure will be and what equipment will be used

4)     What data will be collected and who will be in charge of each job for the group

Your goal/Guiding Question: Make an effective cold pack that is also low cost for your company and have evidence in order to defend your choice to your classmates.

Salt	Amount (in grams)	Cost:
NH4Cl (ammonium chloride)	1,000	$13.90
NH4NO3 (ammonium nitrate)	500	$8.95
MgSO4 (magnesium sulfate)	100	$1.07
NH4SCN (ammonium thiocyanate)	500	$8.55

Materials:

Consumables:                                                            Lab Equipment:

·        NH₄Cl (ammonium chloride)                       Graduated cylinders (100 mL or 25 mL)

·        NH₄NO₃ (ammonium nitrate)                      Stirrers

·        MgSO₄ (magnesium sulfate)                        Thermometers

·        NH₄SCN (ammonium thiocyanate)             Scale

·        Distilled water                                               Weighing dish

Styrofoam Cups w/ beaker for stability

Safety Precautions:

Follow all normal lab safety rules. All of the salts are corrosive to your skin and moderately toxic to ingest. In addition, take the following safety precautions:

§  Wear chemical-splash goggles the entire time in the laboratory.

§  Handle all glassware with care.

§  Wash your hands with soap and water before leaving the laboratory.

Getting Started: You have three main tasks to reach your goal.

Task 1: What type of data you need to collect:

1.      What type of measurements or observations will you need to make during your investigation?

2.      Is it important to know the change in temperature of the solution or just its final temperature?

3.      How does the amount of salt or the amount of water influence your potential results?

Task 2: How will you collect the data:

1.      How often will you collect data and when will you do it?

2.      How will you make sure that your data are of high quality (reduce the errors)?

3.      How will you keep track of the data you collect and how will you organize it?

Task 3: How will you analyze the data:

1.      How will you calculate the heat energy change in the mixture?

2.      What type of graph could you create to help make sense of your data?

3.      How will you use the cost information to influence your decision?

Your guidelines (the rules):

Ø  Your company wants to produce a small, portable cold pack that can easily fit into a small first aid kit. Thus the pack cannot be too big and/or too heavy.

Ø  Your company is planning to use 60 mL of water in the cold pack.  This is the amount that you must use in your investigation.

Ø  For the cold pack to be effective, the temperature must drop rapidly as close to zero (O°C) as possible.

Ø  Your company wants to spend as little as possible to produce the cold packs to maximize their profits.

Ø  Write out your team’s plan for each of the tasks above.  You may write in paragraphs for each or bullet points.

Ø  Use your prior knowledge from conducting lab investigations about temperature and heat. 

Ø  Your group must work as a team to fulfill your investigation and prepare to defend your choice of cold pack.  Remember that you will need to make a claim and have evidence to back it up.

Ø  You will need sign off from Ms. Cotta on your initial plan before any testing 

Requirements in your lab report:

1.     Plan for experimentation

2.     Jobs for each person

3.     Data Table

4.     Graph

5.     Evidence

6.     Argument template

Argument Template: (what is written in bold is what you need to answer)

The guiding question: What salt is the most effective and low cost to use in a cold pack?

Claim: (What salt are you choosing and explain why)

Evidence: (give at least two pieces of evidence why you chose that salt for your cold pack)

Justification: Explain why your evidence is relevant and important to your claim.

HW #7 for 3/29

1) HW #7: pg. 353-5 #23,26,28, 50-53
2) Take Home Lab #4 due Tues. 3/29
3) Pi night Thur. 3/31
4) Earthwatch application due 3/28

Earthwatch Research opportunity

Below is the link to apply for a new Earthwatch research trip.  It is open for 15-18 year old females from Los Angeles.  10 students will be chosen for a week long trip in Colorado.  Students must have an interest in a STEM career and commit to post-trip activities to spread the word about the science research and Earthwatch.  Deadline is March 28th to apply!  If you have questions e-mail me: julianne.cotta@lausd.net.  You will also need to get a recommendation from me so e-mail to tell me that you are applying as soon as possible so I can get your recommendations done!

http://earthwatch.org/education/student-fellowships/projectvault

HW #6 for 3/17

1) HW #6: pg. 333 #4-6, pg. 353 #14
2) Take Home Lab #4 due Tues. 3/29
3) Math/Science night Thur. 3/31

Take Home Lab #4

Take Home Lab #4:  Finger Thermometer

Question: Can your finger be used as an accurate thermometer?

Safety: Only warm water and refrigerator-cold water should be used for this activity. If the activity becomes uncomfortable at any time, stop immediately. Clean up any spills to prevent slipping and falling.

Materials: 3 cups with cold water, room temperature water, and warm water

Procedure: You can put your finger in a cup of water and determine if it is hot or cold. But how accurate is your finger as a thermometer? In this activity, you will find out if your finger is more of a temperature detector or a detector of changes in temperature.

1. Get three drinking cups ready with a wide enough mouth that allows you to put your finger in the water.

2. In the left cup, put cold water either from the refrigerator or tap water with a couple of ice cubes in it. In the middle cup, put room-temperature tap water. In the right cup, put warm tap water.

3. Put a finger from your left hand in the left (cold) cup and put your right finger in the right (warm) cup of water. Wait 30 seconds, then put both fingers in the middle cup. Think about how the water feels to each of the fingers.

Post-Lab Questions:

1. How did the water feel to your left hand? How did the water feel to your right hand?

2. Is your skin a temperature detector or a change-in-temperature detector?

3. How is this similar to the optical illusions where you stare at a colored object for 30 seconds and then stare at a blank wall? If you have not seen on of these before, use your favorite online search engine to search for “American Flag Optical Illusion.”

Part 2:

Procedure:

Find a smooth object (such a sheet protector, plastic cover of a composition book, or other smooth piece of plastic) and a sheet of paper. Set the smooth object near carpet. For 30 seconds, rub the fingers of your left hand on the carpet and the fingers of your right hand on the smooth object. After 30 seconds, rub the fingers of both hands on the sheet of paper.

Post-Lab Questions:

1. How does the paper feel to your left hand? How does it feel to your right hand?

2. How is this similar to the finger thermometer?

Energy Changes Lab

Energy Changes Lab                                                

Procedure:

1.  GOGGLES MUST BE WORN AT ALL TIMES UNTIL EVERYONE HAS CLEANED UP!

2. Measure the designated amount of liquid and record the temperature of liquid in the graduated cylinder with the thermometer.

3. When not using the thermometer AND stirrer place on your paper towel and not on the table.

4. Stir together your two chemicals into the Styrofoam cup and record the temperature after mixing.

5. Dump your chemicals in the large beaker in the fume hood. Wash out your Styrofoam cup, thermometer and stirrer in the sink.

6. When measuring solid chemicals make sure to use your weighing dish and zero out your scale.

7. Carefully stir your water into your solid chemicals and always replace stirrer on the paper towel.

8. Make sure that your lab table when you are finished looks the same as it began.

9. ALERT MS. COTTA TO ANY SPILLS OR BROKEN EQUIPMENT IMMEDIATELY!

Part 1:

Reaction between HCl and NaOH Data Table

Volume of 1.0 M HCl  in mL (close to 15 mL as possible)
Volume of 1.0 M NaOH in ML (close to 15 mL as possible)
Temperature of HCl before mixing (C⁰)
Temperature of NaOH before mixing (C⁰)
Temperature of mixture of HCl and NaOH (C⁰)

Part 2:

Reaction between NH₄NO₃ and H₂O

Mass of NH4NO3 (close to 8 g as possible)
Volume of H2O in ML (close to 15 mL as possible)
Temperature of H2O before mixing (C⁰)
Temperature of mixture  (C⁰)

Part 3:

Reaction between NaOH and H₂O

Mass of NaOH (close to 8 g as possible)
Volume of H2O (as close to 50 mL as possible)
Temperature of H2O before mixing (C⁰)
Temperature of mixture  (C⁰)

Part 1:  Reaction between HCl and NaOH Data Table

Temperature of mixture (C⁰): 

Temperature of HCl before mixing:          

Difference between two temperatures:  

Increase or decrease in temperature ?:                            Exothermic or endothermic ?:

Part 2:  Reaction between NH₄NO₃ and H₂O Data Table

Temperature of mixture (C⁰): 

Temperature of H₂O before mixing:         

Difference between two temperatures:                          

Increase or decrease in temperature ?:                            Exothermic or endothermic ?:

Part 3:  Reaction between NaOH and H₂O Data Table

Temperature of mixture (C⁰): 

Temperature of H₂O before mixing:         

Difference between two temperatures:                          

Increase or decrease in temperature ?:                            Exothermic or endothermic ?:

Questions:

1. What happens to the energy in an exothermic reaction?

2. What happens to the energy in an endothermic reaction?

3. Which of the reactions were exothermic?

4. How do you know it was exothermic? What is your evidence?

5. Which of the reactions was endothermic?

6. How do you know it was endothermic? What is your evidence?

7. Draw a model showing the flow of energy in Part 1 & Part 2 of the laboratory.

8. Which of these examples is exothermic, endothermic and explain why (Remember to think about what is happening to the molecules!).

            a. A lightstick is cracked and begins glowing

            b. Making ice cubes

            c. Cooking an egg

HW #5 for 3/15

1) HW #5: pg. 353 #6-9
2) Pi practice 3/30 after school& Pi night 3/31

HW #4 for 3/14

1) HW #4: pg. 329 exer. 10.2, pg. 330 exer. 10.3, pg. 332 exer. 10.4, pg. 333 #3

Exothermic/Endothermic Pack Lab

Exothermic/Endothermic Pack Lab

Pre-Lab ?’s
1. Explain the difference between an exothermic and endothermic reaction.

2. Is this a physical or chemical change? Explain why.

Lab ?’s:

1. Record the temperature of the thermometer before putting it in both packs. Make sure to use correct units.

2. Record the temperature of the thermometer after it is in the “cold” pack.

3. How does the “cold” pack feel to your hand?

4. Record the temperature of the thermometer after it is in the “hot” pack.

5. How does the “hot” pack feel to your hand?

6. Calculate the difference in temperature between the packs:

“Cold” pack temperature:      _______                        “Hot” pack temperature:        _______

Before temperature:                _______                        Before temperature:                _______

Difference in temperature     _______                       Difference in temperature     _______

7. Which pack involves an exothermic process? What is your evidence?

8. Which pack involves an endothermic process? What is your evidence?

9. Why did the temperature change around the packs? Explain what is happening to the molecules because of the packs.

10.  Explain why measuring the temperature with a thermometer is more effective than simply feeling the packs to identify the process.

Water & Dye Exploration Lab

Water & Dye Exploration

Part 1: Observation

          Make observations about the water in both beakers with your partner. Make at least four observations. Record them in your composition book.

Part 2: Hypothesis

          Two drops of dye will be placed in each of the beakers. What do you think will happen when these are placed in the beakers? Think about that there are molecules of water and dye and discuss with your partner. Write down your hypothesis of what will happen in each of the separate beakers.

Part 3: Observation

          Make detailed observations with your partner after what happened when the dye was placed in the beakers. You can make more measurements and you may use your phone to time if you would like. Write down at least four observations and record them in your composition book.

Part 4: Explanation

          Discuss with your partner about why the dye and water acted differently in the cold water versus the hot water. Remember this is chemistry class and use what you have learned in your explanation about molecules.  Record your explanation in your book.

HW #3 for 3/10

1) HW #3: pg. 325 #2, 5-7
2) Pi day is postponed until Thur. 3/31—practice Tues. 3/30
3) Late comp books turn in on Friday

HW #2 for 3/8

1) HW #2: pg. 327 exer 10.1, pg. 353 25 a, b, d (CORRECTION) 2) Pi day practice Wed. Mar. 9th after school 3) Late comp books turn in on Friday

HW #1 for 3/7

1) HW #1: pg. 319 #1-4 (pre-reading ?’s)
2) Read Chapter 10
3) Pi day practice Wed. Mar. 9th after school

HW #10 for 3/3

1) HW #10: pg. 697 #1-7, 12
2) Late HW due Thur.
3) Nuclear test on Thur. 3/3
4) Composition books due Friday

Study Guide for Chapter 19 Test

--Be able to explain what is an isotope and how they are different
--Be able to write and balance nuclear equations for alpha and beta particles
--Know what makes up a beta particle, alpha particle and gamma ray radiation
--Understand radiocarbon dating and how to tell the difference between age of samples and what it is used for
--How to calculate the half-life from the amount of sample left or how much time has passed, how to calculate how much sample is left
--Be able to explain what the half-life tells you about a nuclide
--Be able to explain the difference between fusion and fission
--Know how fission reactions and fusion reactions produce energy
--Know the parts of the nuclear reactor and their function
--Know how the different types of radiation (beta, alpha & gamma) ray differ in amount of energy and penetrating ability
--Know the symbols for gamma, alpha and beta