Introductory Experiments and Procedures

Laboratory Manual

Introductory Experiments and Procedures

Chemistry I

Name ______

Period______

Lab Station _____

Mr. Gallagher

Room 132

Contents:

Introductionp. 2

Lab #1 Observations of a Burning Candlep. 3

Lab #2 Percent Oxygen in the Atmospherep. 7

Lab #3 Using the Bunsen Burnerp. 8

Lab #4 Separation of a Simple Mixturep. 11

Lab #5 Classification of Matterp. 14

Lab #6 Density Labp. 16

Lab #7 Percent Sugar in Sodap. 22

Lab #8 Testing the Mettle of Metalp. 24

Lab #9 Striking It Richp. 27

Lab #10 Emission Spectroscopyp. 29

Lab #11 Types of Chemical Bondsp. 33

Lab #12 Polar and Nonpolar Moleculesp. 37

Lab #13 Microscale Crystallizationp. 40

Lab #14 Pyrolysis of Woodp. 43

Lab #15 Formula of a Hydratep. 45

Lab #16 Types of Chemical Reactionsp. 47

Lab #17 The Iron Chemistp. 55

Lab #18 Copper Cycle Labp. 57

Lab #19 Serial Dilutionsp. 62

Lab #20 Acid-Base Properties of Com. Sub.p. 65

Lab #21 Acid-Base Titrationp. 66

Lab #22 Heat of Combustion Labp. 68

Lab #23 Radioactive Decay and Half-Lifep. 71

Common Laboratory Equipment Listp. 74

Lab Drawer Equipment Listp. 75

Interpreting Chemical Hazard Labelsp. 76

Unit Conversions and Formulasp. 78

Rules for Proper Graphing Techniquep. 79

Chemistry I Course Guidelinesp. 80

Student Safety Contract Rulesp. 81

Student Safety Contract Sign-off Sheetp. 83

Lab Partners:

NamesPhone #email

______

______

Introduction:

The study of chemistry is vital to understanding the natural world around you. The principles of chemistry are at the heart of nearly every aspect of life that you perhaps take for granted, but nevertheless, depend upon every day. The agricultural, automotive, cosmetics, energy, food service, pharmaceutical, and plastics industries, just to name a few, are directly dependent upon an in-depth understanding of chemistry. New advances in chemistry will eventually have a positive impact on the quality of your life. Chemists will play a major role in finding ways to clean up the environment, develop alternative sources of fuel, and increase crop yields around the world. In addition to all of these practical benefits, chemistry is a fascinating subject, worthy of study for curiosity’s sake.

Chemistry is also an experimental science. Experimentation is the key to discovery and valid experiments depend on accurate measurements and detailed observations. Therefore, we will be focusing on measurement and observation techniques in our first unit. One of the main objectives of this course is for you to develop the thinking skills and habits of a scientist. Here is a partial list of some of these characteristics.

Scientists:

• Pay attention to detail.
• Are careful to record their observations and results
• Look for connections.
• Never stop asking questions.
• Are not afraid to try new things.
• Talk to other scientists about their results and ideas.

The laboratory activities in this unit are designed to challenge you to utilize these skills. As the year goes on, you will need to employ these skills in order to succeed in this class, and hopefully you will utilize them for the rest of your life.

“The most important of my discoveries have been suggested to me by my failures.”

~ Sir Humphrey Davy

Lab #1Observations of a Burning Candle

“The Greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.” ~Stephen Hawking

Objectives:

1. To improve your observation skills.

2. To learn to ask questions that lead to discovery.

3. To develop a hypothesis of the process of the burning of a candle based on evidence derived from your observations.

Note: Include labeled drawings with all of your observations.

Part A – Initial Observations

Procedure:

Light a candle and record your observations with as much detail as you can. Here are some suggestions to help you observe more thoroughly: What are the colors of the flame? What is the shape of the flame? Is the candle’s flame hollow? What is the color and shape of the wick? Does the wick give visible evidence of being hot? Does the wick get longer as the candle wax is consumed? Is the wick combustible? Does the wick burn right at the surface of the candle wax?

Observations:

Unanswered questions:

Part B - What’s in a Flame?

Blow gently at the candle flame through a horizontal straw that is held about one inch from the flame. Start at the top and work down. What do you see? Record your observations in the form of several labeled diagrams. You may want to include this method of recording observations throughout this lab.

Observations:

Part C – Where There’s Smoke!

Blow out the flame. What do you see? Describe the smoke. From what part of the candle does the smoke originate? What is the last site of smoke generation? Hypothesize as to the composition of the smoke. What other event(s) occurs with the cessation of smoke generation?

Observations:

Relight the candle and allow it to burn for about a minute. With a lighted match in one hand, blow out the candle and hold the burning match in the rising column of smoke about an inch above the candle’s wick. What happens? Does this support your hypothesis about the composition of the smoke?

Observations:

Part D – Scorch Marks

Move a horizontally held notecard (that has been moistened with water on the underside) quickly down over the flame to a height where the card almost touches the wick. Hold the notecard in this position just long enough for the flame to scorch through to the upper side of the card, but not long enough to cause it to burst into flames. (If the card begins to burn, toss it into the sink and run water to extinguish the flame.) Draw a pattern of the scorched area on the top of the card. Note the shading.

Observations:

Part E – The Chimney Effect

Wind a length of copper wire (16 gauge or heavier) around a pencil about ten times, leaving enough uncoiled to serve as a handle. Carefully slip the coiled wire off the pencil. Lower the coiled portion over the flame so that the flame is passing through the center of the coils and the copper coils wrap around the flame. You may need to vary the height of the coiled wire to achieve the desired effect. Record your observations.

Observations:

Vary the length of the coiled portion and the spacing between the individual coils. Note how each affects the candle flame.

Observations:

Crush the head of a burnt match into a fine powder and place some of this material into the liquid in the bowl of the burning candle. Observe the motion of these particles in the liquid.

Observations:

Part F – Wikipee?

Lengthen the wick to about 1 cm by removing some of the wax. Light the candle and allow it to burn for a minute or so. Place the edge of a clean scoopula against the wick about halfway up the wick. Do not allow the scoopula to touch the wax. Observe for at least one minute and record your observations.

Observations:

Analysis and Conclusions:

Based on all of your observations propose a hypothesis for how a candle burns. Describe the entire process. Be specific. Include all of the components of the candle; the solid wax, the melted wax, the wick, the flame, and any other relevant facts. Be sure to refer to your observations in parts A-F to support your hypothesis.

Grading:

Observations(Completion)Part A(2)___

Part B(2)___

Part C(3)___

Part D(2)___

Part E(3)___

Part F(2)___

Observations (Quality)

Excellent - Thoughtful & Detailed6

Good - requires more detail/thought4

Average – be more observant3

Poor – superficial2

Conclusion(5)___

Total(25)___

Lab #2 Percent Oxygen in the Atmosphere

Objective: In this lab you will be determining the percentage of oxygen in the air you breathe.

Procedure:

1. Clean the outside of a large ignition tube with alcohol and let dry.
2. Obtain a metric ruler and glass marking pencil. Starting from the open-end of the tube mark every centimeter on the outside of the tube with the marking pencil.
3. Fill a 400 mL beaker about ¾ full with tap water.
4. Obtain a small piece of steel wool. Prepare a 50:50 mixture of vinegar and water by mixing 10 mL of vinegar with 10 mL of water in a beaker. Soak the steel wool in a 50:50 mixture of vinegar/water for 1 minute. Remove the steel wool and carefully squeeze out any excess solution.
5. Pull the steel wool apart to increase the surface area. Push the steel wool into the marked ignition tube with a stirring rod.
6. Cover the end of the tube with your finger and invert tube into beaker of water.
7. Every 5 minutes, move the test tube so that the water level inside the tube is equal to the water level in the beaker. Record the height of the water.
8. Continue to measure and record the height every five until the water level stops changing. Allow the tube with steel wool to sit over night.
9. Carefully measure the height of the water and record.
10. Record the color of the steel wool.

Analysis: (Complete on separate paper)

1. Complete the following calculation;

distance water traveled up in the tube

------x 100% =

total length of tube

1. Where did the oxygen go?
2. Were the changes that you observed physical or chemical? Explain.
3. Air is about 20.8% oxygen. How does your value compare to this value? Calculate the percent error for your value and propose some reasons as to why your value is different.
4. Write a procedure to determine the mass of oxygen that was removed from the air in the tube.

Grading Rubric:Lab procedure and technique___ (5)

Observations and results___ (3)

Analysis Questions (2,3)___ (3)

Analysis Questions (4,5)___ (4)

Total___ (15)

“All truths are easy to understand once they are discovered; the point is to discover them.” ~ Galileo Galilei

Lab #4 Separation of a Simple Mixture

Objectives:

1. To separate a mixture of iron, sulfur and salt.
2. To recover as much of the original mass as possible.

3. To learn important laboratory techniques.

Pre-Lab:

Define the following terms:

1. Pure substance –

1. Element –

1. Compound –

1. Homogeneous mixture –

1. Heterogeneous mixture –

Procedure:

1. Mass a clean, dry watch-glass.
2. Place a scoop of the iron-sulfur-salt mixture on the watch-glass, and determine the mass of the mixture.
3. Use a magnet to remove the iron from the mixture. Transfer the iron to a pre-massed piece of weighing paper. You may need to go over the mixture more than once. Determine the mass of the iron.
4. Transfer the sulfur-salt mixture to a 50 mL beaker. Add 25 mL of water and stir with a glass stirring rod to dissolve the salt.
5. Place a piece of pre-massed filter paper in a funnel and place the funnel in a 125 mL Erlenmeyer flask.
6. Filter the mixture and collect the filtrate – the liquid that passes through the filter.
7. Wash the residue in the filter with 15 mL of water and collect the rinse water with the filtrate. Set the filter paper and residue aside to dry.
8. Transfer the filtrate to a pre-massed evaporating dish. Set up a ring stand to hold the evaporating dish and evaporate the water from the filtrate using a #2 flame with the Bunsen burner. Try to avoid spattering during evaporation.
9. Allow the evaporating dish to cool and then determine the mass of the recovered salt.
10. Determine the mass of sulfur once it has completely dried. Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house. Henri Poincaré

Data:

Table 1 – Mass of original mixture

Mass of original mixture + watch-glass______g

Mass of watch-glass______g

Mass of original mixture______g

Table 2 – Mass of iron

Mass of iron + weighing paper______g

Mass of weighing paper______g

Mass of iron______g

Table 3 – Mass of sulfur

Mass of filter paper + sulfur______g

Mass of filter paper______g

Mass of sulfur______g

Table 4 – Mass of salt

Mass of evaporating dish + salt______g

Mass of evaporating dish______g

Mass of salt______g

Table 5 – Summary of results

Mass of original mixture______g

Mass of recovered iron + sulfur + salt______g

Mass difference______g

Analysis:

1. What properties did you observe in each of the components of the mixture?

1. How did these properties help you to separate the components of the mixture?

1. What types of changes (chemical / physical) were involved in the separation of the components of the mixture?

1. List at least 5 specific factors that may have contributed to the mass difference that you observed.

1. What changes could be made to this procedure to increase the accuracy of the results?

Grading Rubric:

Pre-Lab____(2)

Laboratory technique____(5)

Data____(5)

Analysis____(6)

Safety and Clean-up____(2)

Total____(20)

Lab #5 Classification of Matter

“Science is organized knowledge. Wisdom is organized life.”

~Immanuel Kant:

Introduction:Matter can be classified according to its composition and its properties. Upon careful inspection, matter can first be divided into categories based on whether the composition is uniform throughout or non-uniform and therefore, can be separated into distinct parts. Matter that is uniform in composition and properties can be further categorized as either pure substances or mixtures. Finally, those that are pure substances may be either elements or compounds. Elements are pure substances that cannot be broken down into simpler substances by physical or chemical means. Compounds, on the other hand, are pure substances made of two or more elements that can be broken down into simpler substances by chemical means.

Objective: In this lab you will distinguish between elements and compounds based on mass changes that occur during a chemical reaction.

Materials:crucibles (2)sand paper

crucible lid (1)crucible tongs

ring standiron ring

clay triangleBunsen burner

electronic balance

PreLab:Fill in the each box with one of the terms listed below to create a classification scheme that describes all matter.

( Compounds, Elements, Heterogeneous matter, Homogeneous Matter,

Homogeneous mixtures / Solutions, Matter, Pure Substances)

Procedure:

Part 1

1. Set up the ring stand, iron ring, and clay triangle as shown by your teacher.
2. Obtain a clean, dry crucible and record its mass. If you need to use water to clean it, then you will need to heat the crucible for about 3 minutes to dry it completely. Allow it to cool before proceeding.
3. Place about 0.5 g of the white powder into the crucible and record the mass.
4. Place the crucible on the clay triangle and heat it with a #3 flame for 6 minutes. Allow the crucible to cool for 5 minutes, or until it is cool enough to touch.
5. Re-mass the crucible. Calculate the change in mass of the white powder.
6. Dispose of the white powder in the trash.

Part 2

1. While you are waiting for the crucible in part 1 to cool, obtain a second clean, dry crucible.
2. Record the mass of the crucible and a lid.
3. Obtain a metal ribbon and lightly sand its entire surface. Wipe the surface with a Kim-wipe to remove any dust.
4. Loosely coil the metal ribbon and place it in the bottom of the crucible.
5. Mass the crucible and lid with the metal ribbon.
6. Place the crucible on the clay triangle, and place the lid on the crucible so that only a small gap is visible.
7. Heat the crucible for 12 minutes with the hottest flame. Allow it to cool for at least 5 minutes.
8. Re-mass the crucible and lid with the contents. Calculate the change in mass of the metal ribbon.

Data:

Data Table 1:Mass of White Powder Before and After Heating

Mass of crucible and powder before heating______g

Mass of crucible______g

Calculated mass of white powder before heating______g

Mass of crucible and powder after heating______g

Calculated mass of white powder after heating______g

Change in mass of white powder______g

Data Table 2: Mass of Metal Ribbon Before and After Heating

Mass of crucible, lid and metal before heating______g

Mass of crucible and lid______g

Calculated mass of metal ribbon______g

Mass of crucible, lid and metal after heating______g

Calculated mass of metal (remaining)______g

Change in mass of metal ______g

Analysis: [Refer to the stated objective for the lab to answer these questions.]

1. Based on your calculation for the change in mass that you observed in part 1, classify the white powder that you placed in the crucible according to the classification scheme that you created in the pre-lab.

1. Classify the product that was obtained after heating the white powder.

1. Based on your calculation for the change in mass that you observed in part 2, classify the metal ribbon that you placed in the crucible.

1. Classify the product that was obtained after heating the metal ribbon.

1. Hypothesize as to what may have happened in each of the crucibles to cause the changes in mass. Be as specific as possible.

Grading Scale:

PreLab(3)____

Data Table 1(3)____

Data Table 2(3)____

Analysis#1(1)____

2(1)____

3(1)____

4(1)____

5(4)____

Total(17)____

Lab # 6Density Lab

An experiment is a question, which science poses to Nature, and a measurement is the recording of Nature's answer. ~Max Planck

Objectives:

1. To learn the proper use of significant digits in calculations involving measurements.

2. To identify seven unknown metals from their measured densities.

3. To learn proper graphing techniques and analysis.

Part A - Identifying Unknown Metals

Procedure:

1. Mass each metal object on the balance that is provided at that station.

2. Use the measuring instrument available at each station to determine the volume of the metal object.

3. Calculate the density of the metal and report it to the correct number of significant digits.

4. Look up the densities of the metals listed in reference table A.

5. Identify each of the metals A – G.

Reference Table A1

Accepted Densities of Metals

Density (g/cm3)

Use your periodic table to find the densities of the metals in Table A.