HW #11 for 5/4

1) HW #11: pg. 775 #1, 3-8, pg. 779 #26-27, 31-32, 37
2) Test & late HW on Monday 5/4
3) Catch up on take home labs
4) Drop in Fri. 5/1 after school for questions about test and HW, also extra credit clean up for lab

Take Home Lab #9

Take Home Lab #9: The Mole

Question: What does a mole of different substances look like?

Safety: Baking soda can harm your eyes. Dispose of all chemicals, clean up all spills, and wash your hands when finished.

Materials: Balance, pre-1982 pennies, water and baking soda.

Procedure: Because atoms and molecules are so small, chemists created a quantity called a mole that represents a large number of atoms. The unit of a mole is like a dozen in that it represents a certain number of atoms or molecules. It is a very, very, very large number but the same idea as a pair, a dozen, a gross, and so on. A pair is 2 items, a dozen is 12 items, a gross is 144 items, and a mole is 6.0 x 10²³ items (molecules or atoms). That is 600,000,000,000,000,000,000,000 items in a mole. But what does a mole of a substance look like? You will find out in this activity.

            In this activity, you will use your balance to measure out approximately 1 mole of different substances. Recall from the experiment where you built your balance that the density of water is 1.0 g/mL. Therefore, 1 mL of water has a mass of 1 g. You will use this information and the periodic table to determine how much of each substance composes a mole.

            The periodic table tells you the mass of a mole of each element. For example, the mass of a mole of carbon is 12.011 g. To find the mass of a compound, you simply add up the masses of each element that makes up the compound. For example, a mole of calcium carbonate (CaCO₃) would have a mass of approximately 100 g (40.078 + 12.011 + 3[15.999] = 100.086g). Your balance is not sensitive enough to measure the 0.086 grams, so for take-home labs we will just ignore that part and round it to 100 g.

            Use your balance, the periodic table, and the known density of water to determine 1 mole of the following items. Describe how much of each makes up 1 mole (for example; seven and a half pennies, a large handful of sand). If a mole of the substance is very large, you may measure half a mole or one-tenth of a mole and then describe what a full mole would look like.

Data:

Substance	Number of grams	Description
Pennies (pre-1982 pennies are pure copper and post-1982 pennies are not, so use pre-1982 pennies)
Water (H2O)
Sand (Pure sand is SiO2; assume that your sand is pure.)
Baking soda (sodium bicarbonate, NaHCO3)

Post-Lab Questions:

1. How many 500 mg aspirin tablets would it take to make a mole of aspirin? (C₉H₈O₄)?

2. Which would be heavier, a mole of sodium chloride or a mole of potassium chloride? Explain.

3. Why can you not determine the mass of a mole of most mixtures?

Study Guide for Chapter 20 & 21 Test on Monday 5/4

Chapter 20:
--what is a hydrocarbon
--know what is the difference between a saturated and unsaturated hydrocarbon
--difference between an alkane, alkene and alkyne
--know the formulas to figure out the chemical formula for alkanes, alkenes and alkynes
--know how to draw structures for alkanes, alkenes and alkkynes which correct branch and numbers of the carbon positions

pg. 749 test practice
1. C  2. B  3. D  4. C  6. B

Chapter 21:
--know what are the six essential elements to the human body and what are the 30 elements necessary for human life
--know the properties of a protein
--know the difference between a fibrous protein and a globular protein
--know the structures of a protein and the building blocks that create these structures
--know about how peptide bonds link the amino acids together
--know the two secondary structures that proteins can form
--know what denaturation of a protein is and what causes it
--know what an enzyme is and its function
 --know what the lock and key model for enzymes is and what is explains about the enzymes
--know the properties of carbohydrates
--know what are the building blocks of carbohydrates
--know the forms of carbohydrates such as starch and cellulose
--know what the building blocks of nucleic acids
--know the bases for DNA and RNA
--know the properties of lipids and the types of lipids such as fats, steroids, waxes and cholesterol

pg. 781 test practice
1. A  2. B  3.  C   5. D   6. A  8. adenine complements thymine, cytosine complements guanine

Enzymes in Action Lab

Enzymes in Action

Problem: Are there enzymes in your cells that react with dangerous chemicals in your cells?

Introduction: There are thousands of different types of enzymes found in our body. Enzymes are composed of proteins, which are composed of polymers made of long chains of amino acids.

Cells in your body are continually making dangerous chemicals that have to be destroyed in order to keep your cells functioning properly. The enzymes in your cell break down these dangerous chemicals into harmless chemicals in order to keep your cells safe. One such enzyme is called catalase, its job is to speed up the reaction to break down hydrogen peroxide (H₂O₂) in your cells. It breaks down hydrogen peroxide into harmless chemicals for your body: water and oxygen.

Hydrogen peroxide is created by normal cell processes as a byproduct from chemical reactions. However, if this hydrogen peroxide is not broken down, the cell would be poisoned and die.  You will be looking at catalase enzymes in chicken liver cells.  These cells are no longer alive, but the enzymes are still intact and able to survive as long as they are refrigerated.

Part A: Normal Catalase Reaction

Steps:

1. Add 2 mL of water to 1^st test tube. Add a small cube of liver and record your observations in data table. Feel the test tube for any temperature change.

2. Add 2 mL of hydrogen peroxide to 2^nd test tube. Add a second cube of liver and record your observations. Feel the test tube for any temperature change.

3. Add 2 mL of hydrogen peroxide to 3^rd test tube. Take a cube of liver and mash it up with a fork and add to test tube. Record your observations and feel the test for any temperature changes.

Data:

Size and condition of liver	Experimental Liquid	Observations	Rate of reaction 0-5: 0=no reaction, 1= slow, 5=very fast
1 cm cube chicken liver	2 mL H2O
1 cm cube chicken liver	2 mL H2O2
1 cm cube chicken liver (mashed)	2 mL H2O2

Questions:

1. What is the purpose of putting the liver in water? Why is this a necessary step?

2. Describe the difference between the whole cube of liver and the mashed up cube of liver? What could account for the difference in the two reactions?

3. Is the reaction that occurred exothermic or endothermic? Explain why.

4. Balance the equation that occurs that breaks down the hydrogen peroxide. Identify the reactants and products by name.

H₂O₂ àH₂O + O₂

Part B: Second catalase reaction

Steps:

1. Pour off the remaining liquid from your liver cube from test tube #2 into a fourth test tube.

2. Add a new piece of liver to this liquid. Write your observations.

3. Add 2 mL of hydrogen peroxide to the liver cube in test tube #2 and record observations.

Questions:

1. Identify by name what is the remaining liquid that you poured into the test tube.

2. Describe your observations after the liver was added and rate the reaction rate from 0-5.

3. Describe your observations after the hydrogen peroxide was added to test tube #2. Rate the reaction rate from 0-5.

4. Is the catalase enzyme in your cells reusable? What is your evidence?

Part C: What tissues contain catalase?

Steps:

1. Dump the liver into the trash bowls by the sinks. Make sure NO liver is dumped into the sink. Wash out your test tubes and return to the test tube rack.

2. Add 2 mL of hydrogen peroxide to each to three test tubes.

3. Add to test tube #1 a small piece of potato, to test tube #2 a small piece of apple, to test tube #3 a small piece of beef. Record your observations. Place all samples in trash bowl and wash out test tubes.

Questions:

1. Rate the reactions of the three substances from 0-5 for reaction rate:

Potato: _____________

Apple: _____________

Beef: ___________

2. Based on your observations, which tissues contain catalase?

3. Do some tissues contain more catalase than others? How can you tell?

Part D: What Is the Effect of Temperature on Catalase?

Steps: Hot water bath

1. Put a piece of liver into the bottom of a clean test tube and cover it with a small amount of water.

2. Place this test tube in a boiling water bath for 5 minutes. (Use a test tube holder for hot test tubes!)

3. Remove the test tube from the hot water bath, allow it to air cool, then our out the water.

4. Add 2 mL of hydrogen peroxide.

Steps: Warm and ice water bath

1. Put equal quantities of liver into 2 clean test tubes and 1 mL of H₂O₂ into to two other test tubes.

2. Put one test tube of liver and one of H₂O₂ into an ice bath. Place the other set in a warm water bath (not boiling).

3. After 3 minutes, pour each tube of H₂O₂ into the corresponding tube of liver (pour cold H₂O₂ into cold liver and warm H₂O₂ into warm liver) and observe the reaction.

Questions:
1. What was the reaction rate for the boiled liver and hydrogen peroxide?

2. What is the reaction rate for the cold liver/peroxide?

3. What is the reaction rate for the warm liver/peroxide?

4. How does temperature affect the rate of reaction? At what temperature do you think that the enzyme catalase is most effective?

Part E: What Is the Effect of pH on Catalase Activity?

Steps:

1. Add 2 mL of H₂O₂ to each of 5 clean test tubes. Measure the pH of the liquids.

Tube 1—add 2 mL  of acetic acid  pH = _____

Tube 3—add 2 mL  of baking soda (base)  pH = _____

Tube 5—add 2 mL drops of water (neutral)   pH = _____

2. Now add liver to each of the test tubes (try to do it all at about the same time, so you can easily compare).

Rate of Reaction for : Acid _____   Neutral _______     Base _______

Questions:

1. Write data from your steps.

2. How does pH affect the rate of reaction? At what pH do you think that the enzyme catalase is most effective?

Part F: Design your own experiment

       Some people are lactose intolerant, meaning that they cannot eat dairy products because they are unable to digest the lactose (sugar from milk) in milk products.  People that are lactose intolerant lack the enzyme (lactase) that helps to break down the lactose.  There is a pill available called lactaid that helps to break down this sugar by giving them their missing enzyme, lactase. 

       Benedict’s solution is an indicator that shows the amount of glucose (simple sugar) present in a sample. Like a pH indicator it will change color based on the amount of glucose present. When lactose is broken down by the enzyme, more and more glucose will be present and the sample will change color to show that increase in sugar.

       How could you design an experiment to show how quickly lactaid breaks down lactose? What would be your steps that you would follow in your experiment?

1. Write down your steps to your experiment and be specific to what you would you do and how much materials you would use and need. 

2. What could you experiment with to show different experimental conditions to show in what conditions the lactaid is most effective? (Hint: think about the different trials you do with the hydrogen per

HW #10 for 4/30 & 5/1

1) HW #10: pg. 778 #11-21
2) Test & late HW on Monday 5/4
3) Catch up on take home labs
4) Drop in W & F to prepare for test

HW #9 for 4/28 & 4/29

1) HW #9: pg. 761 #1-2, 4-7, pg. 778 #1-4
2) Test on Monday 5/4
3) Catch up on take home labs

Gluep Lab

Gluep Lab

Problem: Can you make a cross-linked polymer from white glue?

Introduction:

Polymers are large chain-like molecules that are built from small molecules called monomers. You have used polymers, such as Teflon and nylon, in everyday life. Polymers are also used in plastic bottles, carpets, clothing, and synthetic rubber.

Cross-linked polymers consist of polymer chains connected by chemical bonds. Substances such as Slime or Gak are cross-linked polymers. Cross-linking polyvinyl acetate (present in most white glues) with laundry borax can make a substance called gluep.

In this lab activity you will make gluep from white glue and laundry borax. You will also test its properties.

Procedure:

Part 1: Making Gluep

1. Pour about 1 tablespoon of white glue into your plastic cup.

2. Add 15 mL of water to the white glue and stir until completely mixed. Add a drop or two of food coloring. Mix. Make and record careful observations.

3. Add 10mL of borax solution to the glue and water mixture and stir. Make and record careful observations.

4. Use the plastic spoon to transfer the gluep onto wax paper. Use a paper towel to get rid of excess liquid.

5. Squeeze out the excess liquid and roll the gluep into a ball.

6. Write a paragraph discussing your observations while making gluep.

Part 2: Testing Gluep’s Properties

1. Does a ball made from gluep bounce? Drop your ball from a height of 2 feet onto a non-carpeted floor. Measure and record how high the ball bounces.

2. Some substances you can buy at a toy store can lift an image from the newspaper. Can gluep do this?

Part 3: Reacting Gluep with Vinegar and Baking Soda

1. Place a small ball (1 cm diameter) of gluep in your cup. Add about 20 drops of vinegar and stir. Record your observations.

2. Add about half a teaspoon of baking soda to this mixture and stir. Record your observations.

Data/Observations:

1. Write a paragraph discussing your observations when making gluep.

2. How high could your gluep ball bounce?

3. Can gluep lift an image from the newspaper?

4. Explain what happened when vinegar was added to gluep? What happened when baking soda was added?

Analysis and Conclusions:

1. Write a paragraph summarizing the properties of gluep.

2. Explain your observations when gluep reacted with vinegar and baking soda. Explain what happened to the polymer with the vinegar (a weak acid) was added and then what happened when baking soda (a weak base) was added.